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The predictability of the histological features of uremic bone disease by non-invasive techniques
Metab.
Bone
Dis.
& Rel. Res.
Metabolic Bone Disease 8 Related Research
1, 39-44 (1978)
@ by S.N.P.M.D. (Paris 1979)
The predictability of uremic bone
of the histological features disease hy non-invasive techniques
KEITH A. HRUSKA, STEVEN L. TEITELBAUM, ROBERT KOPELMAN, CATHERINE A. RICHARDSON, JAMES DEBMAN, KEVIN MARTIN, AND EDUARDO SLATOPOLSKY Renal Division, Department of Medicine, Washington University, Division of Bone and Mineral Metabolism, The Jewish Hospital St. Louis, Missouri 63110.
Department of St. Louis,
of Pathology Washington,
Address
Med.
Div.
for correspondance
and reprints:
Keith
A. Hruska,
Abstract Forty-six uremic patients on chronic hemodialysis underwent bone biopsy to ascertain the relationships of serum biochemistry, radiographic analysis, and bone mineral analysis to bone histomorphometry. Circulating levels of immunoreactive parathyroid hormone and alkaline phosphatase, as well as radiographically apparent subperiosteal resorption, are most predictive of osteitis fibrosa. Bone densitometry correlated poorly with some parameters of osteitis fibrosa and not with histologically measured bone volume. None of the clinical parameters tested are predictive of osteomalacia. These findings underscore the necessity of bone biopsy to accurately assess the chronically uremic skeleton.
Key Words: Hyperparathyroidism Bone Biopsy metry.
- Serum
Biochemistry
- Osteomalacia - Bone Morpho-
Introduction Renal osteodystrophy is a generic term which a host of skeletal abnormalities encompasses The morphological attending chronic renal failure. alterations include combinations of osteitis fibrosa, osteomalacia, osteosclerosis, and osteopenia (Jowsey et al., 1969; Duursma et al., 1972; Bordier et al., 1975; Duursma et al., 1974; Sherrard et al., 1972; Malluche et al., 1975). In recent years, significant advances have occurred in the treatment of renal The potential complications of some osteodystrophy. of these therapeutic modalities have underscored the necessity of exact histological characterization of the skeletal lesion (Pierides et al., 1976). While the introduction of simple methods of obtaining trocar biopsies of the ileum, and the development of techniques of preparing well preserved, non-decalcified thin histological sections of bone have made this delineation possible, these procedures are not widely available. We have, therefore, undertaken a study to determine if the histology of the uremic skeleton is predictable by the use of readily available, non-invasive clinical techniques. These results demonstrate that high levels of circulating immunoreactive parathyroid hormone (IPTH), alkaline phosphatase and radiographic evidence of subperiosteal
Int.
Renal
PHILIP MILLER.
and Laboratory Medicine, and University School of Medicine,
499 S Euclid
St. Louis,
MO. 63110.
resorption reflect the presence of osteitis fibrosa. On the other hand, the quantity of osteoid. and hence the degree of osteomalacia are not predictable by non-invasive techniques.
Materials
and Methods
studied consisted of 111 patients, all of whom had end-stage renal disease treated by chronic hemodialysis at the Chromalloy American Kidhey Center, St. Louis, Missouri, during the period of June, 1974 to January, 1976. Forty-six (41%) of the total group were selected to undergo bone biopsy on the basis of affirmative consent and an attempt to closely match the clinical findings of the patient population as a whole (Table 1). All biopsied patients were older than twenty years of age. Twelve (26%) were over 50 years of age, and 21 were female. The mean duration of dialysis ranged from five to ninety-six months, with a mean of thirtyseven months. Twenty-nine patients were treated at home, and seventeen were on center dialysis. None of the patients had undergone previous renal transplantation, although three had undergone nephrectomy in preparation for transplantation. None of the patients had recieved corticosteroid or anticonvulsant therapy while on chronic hemodialysis. ~
The population
Dialysis was performed for 5-7 hours, three times a week, using Travenol coil dialyzers (Model U2. 100 or 1451, and the Travenol EJSL 120 bath containing 130 mEq/L sodium,
Table I. Clinical
diagnoses
of renal
disease
in the
study
population.
Diagnosis
Biopsied
ia
Chronic Glomerulonephritis Acute Glomerulonephritis’ Nephrosclerosis Chronic Pyelonephritis Tuberous Sclerosis Diabetes Malignant Hypertension Alports Syndrome Interstitial Nephritis Polycystic Kid.ney Disease Nephrocalcinosis
1
6 10
46 ‘less
than
6 months
disease
course.
Total Dialysis Pooulation 47 2 15 15 2 4 11 2 2 10
111
40
K.A.
2 mEq/L potassium, 3.25 mEq/L calcium, 1.5 mEq/L maanesium. 37 mEa/L acetate. 0.25 a/dl dextrose. All patyents ingested ph’osphate binders t; maintain normal serum phosphorus. Supplemental elemental calcium, sufficient to provide a daily intake Of 1.0-1.5 grams was administered except during periods of hyperphosphatemia. Thirteen biopsied patients had been taking 25,000-100,000 units of vitamin DZ per day for variable periods at some time during their time on chronic hemodialysis. Since this treatment had no significant effect on the relationships between clinical and histological measurements, these patients were not segregated from the total study population for this report.
Biochekical
Determinations
Blood levels of total calcium, phophorus, magnesium and creatinine were determined every six to eight weeks in all patients as previously descritied (Hruska-et al., 1975; Chase et al.. 1974). Alkaline prosphatase was measured every sixteen to twenty weeks by the method of Morganstern et al. (1965). Plasma ionized calcium was examined every twelve fo fifteen weeks using a flowthrough membrane electrode (Orion Research, Cambridge, Massachusetts). lmmunoreactive parathyroid hormone (i-PTH) was determined at the same time employing the CH9 antiserum (Hruska et al., 1975; Chase et al., 1974). The determinants of binding to this antiserum are in the carboxyl terminal portion of the PTH molecule. Consequently, the immunoreactive forms detected include native PTH and carboxvl terminal fragments. These _.__.. fragments are largely eliminated by the kidney and are thus _..-- retained ~~ .~ in chronic renal failure (Martin et al.. 1977; Freitag et al., 1978). The range of I-PTi-l of the group was 9-940 plEq/ml (normal 2-10). All patients, except two who had been parathyroidectomized, had elevated I-PTH levels.
Bone
Histomorphometry
A[[ patients received 750 mg of tetracycline per day orally for three days prior to biopsy. Transiliac bone biopsy having a 0.5 cm internal was performed with a trocar diameter. The specimens, which included both cortices and intervening trabeculae. were fixed in neutral buffered formalin after which they were embeddad, non-decalcified, in methylmethacrylate and cut in sections 5.0 pm thick on a Jung Model K Sledge Microtome (Jung Instruments, Heidelberg, Germany). The entire trabecular area of two sections taken from approximately one-third and one-half the thickness of the core, and stained by a modification of the Goldner technique, was evaluated histometrically using a Zeiss II Integrating Eyepiece at 200X magnification (Bayers, 1977). The tetracycline-based fluorescent parameter was quantitated in the same fashion using two unstained IO pm thick sections also taken from different levels of the specimen. The following histological features were quantitated: a) percent total bone volume, or the percentage of trabecular bone covered by osteoid not b) percent relative osteoid volume; or the percentage of trabecular bone matrix which is unmineralized: c) percent trabecular surface covered by osteoid; d) percent osteoblastic osteoid surface, or the percentage of trabecular bone covered by osteoid lined by typical, plump osteoblasts: e) percent non-osteoblastic osteoid surface, of the percentage of trabecular bone covered by osteoid not lined by typical, plump osteoblasts: f) percent osteoclastic resorptive surface, or the percentage of trabecular surface characterized by resorptive bays (Howships’s lacunae] in apposition to osteoclasts; g) percent nonosteoclastic resorptive bays not in apposition to osteoclasts; h) number of osteoclasts/mmz of cancellous space: i) number of osteoclasts/mmz of cancellous space in apposition to trabecular bone surface; j) number of osteoclasts/mm2 of cancellous space not in apposition to trabecular bone surface; k) mean osteoid seam width. This is a derived value obtained by dividing the osteoid volume by its absolute linear extent; I) percent of trabecular surface in apposition to marrow fibrosis; m) the percentage of osteoid seam-mineralized bone interface labeled by tetracycline fluorescence.
Hruska
et al.:
Predictability
of
histology
in uremic
skeleton
These results were compared to those obtained from samples acquired at autopsy from patients suffering sudden death. The controls included eleven males and six females at a mean age of 45.8 +- 20.6 (S.D.) years. The percentage of osteoid seam mineralized bone interface assuming a tetracycline label in our uremic patients was compared to the normal bone biopsies reported by Melsen and Nielsen, 1977. Radiographic (Table
Analysis
II)
All radiologic grading was performed without clinical or histological information available to the observer. The radiographic studies included views of the skull, chest, shoulders, hands, lumbar spine, abdomen and pelvis. For purposes of statistical correlation, resorptive changes were graded for severity and distribution. The hand films obtained for this purpose at the time of iliac crest biopsy were studied by the magnification technique of Meema and Meema, 1972. We also graded random asymmetric ectopic soft tissue calcifications noted especially in the hands and wrists, but also about the shoulders, elbows, hips and knees. Since stress, traumatic and pathologic fractures could not be definitely differentiated from Looser’s zones, these were all considered as fractures. Finally, vascular calcifications, especially involving arteries of the hands and pelvis, were quantitated. Bone
Mineral
Determinations
Bone mineral analysis was performed every sixteen weeks on the mid distal radii of all patients using the Norland Cameron Bone Mineral Analyzer (Cameron and Sorenson, 1963; Cameron et al., 1968). A standard apparatus for repositioning das employed. The ratio of bone
mineral content (g/cm) to bone width (cm) was determined. The derived quantity, BM/BW (g/cm2) was compared to data obtained from age and sex matched normal subjects (Mazess and Cameron, 1975). Statistical
Methods
The results of the various studies and the information abstracted from the charts were recorded on specially designed forms, keypunched and entered into a computerized data base using the SAS statistical analysis and data base management system [Barr et al., 1976). Many of the variables subjected to anlaysis were distributed in a distinctly non-normal fashion, a result expected
from the pathological nature of the patient population and the nature of the variables themselves. This non-normality precludes the use of the standard product moment correlation coefficient (r) for assessing the strength of the association in this group of patients. Rather than examining each variable in order to select an appropriate transformation (log, arc sin, or reciprocal), Kendall’s Tau b test which is a non-parametric measure of association was employed (Snedecor and Cochran, 1967). Scatter plots of relationships were also produced and examined to facilitate interpretation of potentially afalse positive* correlation coefficients in the absence of estimated parametric functional relations between the variables. Significance levels were calculated using standard formulae and are presented for reference as the probability that the value of the correlation coefficients (r) were greater than zero.
Results No differences exist between the levels of blood biochemical determinants of the biopsied patients measured at the time of biopsy or during the threemonth period prior to biopsy, when compared to the entire dialysis population (Table III). Furthermore, the biopsies taken from the uremic patients exhibit the classical changes of renal osteodystrophy (Table IV]. There is an abundance of osteoid, osteoclasts, osteoblasts and peritrabecular marrow fi-
K.A.
Hruska
et al.:
Predictability
Table II. The grading
Radiographic
Severity
of
Distribution
of
histology
in uremic
used for analysis of the radiographic
system
Abnormal
Findings
Demineralization
Ectopic
Criteria
1 2 3 4
borderline mild moderate severe
1 2 3 4
subperiosteal resorption base of phalanx subperiosteal resorption midshaft of phalanx sclerosis of vertebral bodies sclerosis beyond vertebral column
1 2 3 4
none slight moderate mineralization
1
none definite < 2.5 cm dia., one site more than one site, all < 2.5 cm one or more, > 2.5 cm
2 3 4
Calcification
1 Fractures
(Looser’s
Zones)
: 4
and Histomorphometric
Parameters
bone interface which assumes a tetracycline also correlated with these two biochemical minants.
LPTH and alkaline phosphatase are the biochemical tests most predictive of the presence of osteitis fibrosa, viz. (dl percent trabecular surface covered by osteoblastic osteoid, (f) percent trabecular surface containing osteoclasts, (h) the number of osteoclasts/mm’ cancellous space, osteoclasts on (il and
Radiographic
Table Ill. Mean population.
serum
alterations
minerals,
also
iPTH plEq/ml
Parameters
As would be expected, radiographically determined osteosclerosis and demineralization respectively,
correlated
iPTH and alkaline
and Histomorphometric
label deter-
(Table VI)
off (j) trabecular surfaces and the (I] ‘percent to marrow fibrosis. trabecular surface in apposition morphological
tissue
Increased relative osteoid volume and percent osteoid surface, which are the histological features most characteristic of osteomalacia (Avioli and Teitelbaum. 1976), are not predictable by biochemical evaluation. However, the width of the osteoid seams correlated with both I-PTH and alkaline phosphatase even though this histological feature was within our normal range. Furthermore, the percentage of osteoid-mineralized
(Table VI
The same
to soft
negatively and less significantly with both ionized and total calcium. Phosphorous and magnesium are even less predictive of the histological lesion.
brosis. A marked deficit in the percentage of osteoid seam-mineralized bone interface which assumes a tetracycline label is also apparent. Interestingly, the increase in osteoid present in the uremic biopsies is due to an increase in the percent of trabecular bone surface covered by osteoid and not to augmentation of the mean osteoid seam width.
Biochemical
equal
single arterial plaque scattered noncontinuous plaques longer calcified arterial segments uninterrupted arterial wall calcification
32 4
Calcification
normal
questionable hairline fracture one definite fracture two-four fractures more than four fractures
1 Vascular
findings.
Grade
Parameter
Osteodystrophy
of
41
skeleton
phosphatase
Calcium mgldl
Ca++ mg/dl
determination
Alk.
in biopsied
Phos. I.U.
patients
Phos. mgldl
and in total
Magnesium mg/dl
patient
Creat. mg/dl
ti SD N
327 280 41
10.0 1.2 45
4.4 0.6 41
112 154 45
5.1 1.3 45
2.8 0.3 41
12.2 3.2 45
Biopsied patients M value during 3 months prior to biopsy
G SD N
316 278 80
9.9 1.4 138
4.3 0.7 80
116 152 96
5.1 1.3 138
2.8 0.4 80
12.0 3.3 138
Mean all determinations of entire dialysis population
i SD N
274 281 468
9.9 1.2 1179
4.3 0.7 396
116 136 1194
4.8 11841.8
0”:: 396
12.0 4.3 1164
Biopsied at time
patients of biopsy
IPTH. immunoreactive serum phosphorus minations.
parathyrold hormone Great., serum creatinine
Ca++, ionlzed calcium M = mean - SD =
Alk.
Phos.,
alkaline -
standard deviation
Phos., phosphatase N = number of deter.
42
K.A.
Table IV. Mean
-t
SD of histomorphometric
Histological
determinations
Determined
Table
by non-paired
V. Correlation
Histomorphometric
Mean 21.9 2.0 12.6 1 .o 11.6 0.162 2.2 0.112 0.077 0.035 0 86.6
VI.
between
tests
done
coefficients
Total bone volume Relative osteoid vol. Osteoid surface Osteoblastic osteoid surface Non-osteoblastic osteoid surface Osteoclastic resorptive surface Non-osteoclastic resorptive surface Osteoclast Osteoclasts in appos. to trab. bone Osteoclasts not in appos. to trab. bone Osteoid seam width Trab. surf. in appos. to fibrosis Osteoid seam with tetracycline label r’s with
significant
p values
histology
Mean 22.7 13.4 71.9 5.4 66.5 1.9 9.7 1.5 1.4 0.1 8.0 13.9 51.4
in uremic
and a normal
Hemodialysis
and quantitative
bone
Alkaline Phosphatase
between SubpeResorpt.
Histological Parameters
Only
on serum
Determination
coefficients with significant NS = not significant.
Correlation
on hemodialysis
of
st & i_ & ++++++++ t t
control
patients
skeleton
population.
Significance of differences*
SD 10.3 8.6 13.9 5.0 16 1.8 5.4 1.7 1.6 0.2 6.1 20 30.8
N.S. < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.05 N.S. P < 0.001 P < 0.001
P P P P P P P P P
t test
NS
Total bone volume Relative osteoid volume Osteoid surface Osteoblastic osteoid surface Non-osteoblastic osteoid surface Osteoclastic resorptive surface Non-osteoclastic resorptive surface HG. Osteoclast I.’ Osteoclasts in apposition to trabecular bone not in apposition to J. Osteoclasts trabecular bone K. Osteoid seam width L. Trabecular surface in apposition to fibrosis M. cl0 Osteoid seam with tetracycline label
Table
Predictability
c SD f a.4 -c 2.3 + 13.9 + 1.7 - 12.9 2 0.230 +- 1.5 f 0.121 +- 0.108 + 0.049 c 6.1 f 0 t 22.1
lo.8
A. B. C. D. E. F.
Only correlation 0.005 - 0.0001 -
al.:
Normals
student’s
coefficients
et
of patients
parameter
Total bone volume Relative osteoid volume Osteoid surface Osteoblastic osteoid surface Non-osteoblastic osteoid surface Osteoclastic resorptive surface Non osteoblastic resorptive surface Osteoclast Osteoclasts in apposition to trabecular bone Osteoclasts not in apposition to trabecular bone Osteoid seam width Trabecular surface in apposition to fibrosis O/O Osteoid seam with tetracycline label l
Hruska
histomorphometry
Calcium
NS
Ii:
NS
E
I%
NS
0.62t NS 0.51t
0.3at NS 0.37t
-0.23’ NS -0.28+
0.33’ 0.49t
0.25’ 0.3at
-zst
0.26’ NS 0.27+
0.49t
0.37t
-0.32t
0.30t
0.49t 0.23” 0.50+ 0.42t
095t 0.36t 0.40+ 0.39t
-0.34t NS
!Z
0.36+ -0.25’
0.24’ NS
p values
radiographic
are
portrayed.
grading
Endosteal Cortical Resorpt. Striations
l
=
and bone Distal Clav. Resorpt.
0.05
0.27’
+
=
0.01
- 0.005 -
Osteosclerosis
Demineralization
Fractures
ACr;g;il
cation
cation
0.33+
0.32+
0.33+
0.24’
0.4ot
-0.34t
0.24’
0.33+
0.26.
0.27’
0.31f
portrayed.
*p =
0.05 -
..
0.26.
0.32+ 0.32+
0.26’
=
W&pie. .
0.24’
0.35+
t
histomorphometry.
0.43t
0.32+ - 0.25, 0.35t
- 0.01 -
E
0.01 - +p = 0.01 -
0.005 - tp
= 0.005 -
0.0001.
K.A. Hruska et al.: Predictability
of histology
in uremic
Similar to the levels of i-PTH and alkaline phosphate, the degrees of osteosclerosis and particularly, subperiosteal resorption, correlate with the magniNo radiographic feature tude of oseitis fibrosa. relates to relative osteoid volume or percent osteoid surface. Again, in conjunction with I-PTH and alkaline phosphatase, the degree of subperiosteal resorption relates to the percent of osteoid seam with a tetracycline label.
Table VII. and
and Histomorphometry
E.
1.
J. The mean value of the biopsied patients’ mid and distal shaft mineral content/width ratio respectively is 0.65 2 0.12 (S.D.) and 0.44 -r- 0.10. These values are more than two standard deviations below that of age and sex matched controls (Mazess and Cameron, 1975). While there is progressive loss of mid and distal shaft mineral content/bone width with duration of dialysis (r = 0,25, p <.OOl, densitometric measurements correlate poorly with the morphological features of renal osteodystrophy
(Tabel VII). Discussion The results of this study indicate
that the magnitude of osteitis fibrosa is reasonably predictable in the dialyzed uremic skeleton by non-invasive parameters, specifically I-PTH, alkaline phosphatase and radiographically apparent subperiosteal resorption. On the other hand, the presence of excess osteoid can be evaluated only by bone biopsy. As uremic patients most often have combinations of osteitis fibrosa and osteomalacia, these data underscore the necessity of histological confirmation of the skeletal lesion prior to therapy. Furthermore, if treatment is directed toward amelioration of osteomalacia, its effectiveness can only be appreciated by bone biopsy. Although the presence of increased quantities Of osteoid is essential to the diagnosis of osteomalacia, this morphological feature may exist in the absence of a mineralization defect. Specifically, osteoid may be augmented in states of accelerated organic matrix synthesis such as hyperthyroidism (Melsen and Mosekilde, 1977). The distinction between hyperosteoidosis due to a mineralization defect and that secondary to accelerated matrix synthesis is best made by the use of time-spaced (double) fluorescent tetracycline labels (Meunier et al., 1975). As in our group of patients, however, the presence of osteomalacia may also be established by a paucity of osteoid seams which assume a fluorescent label (Bordier and Tun Chot, 1972). The one feature of osteomalacia which is reflected biochemically and radiographically is percent osteoid seam assuming a tetracycline label. However, as demonstrated in this laboratory, this parameter may be normal in uremic patients despite the presence of a mineralization defect (i.e., osteomalacia) demonstrable by other morphological measurements (Teitelbaum et al., 1977). Consequently, the relationship between I-PTH and the percent osteoid seam assuming a tetracycline label may reflect delayed mineral maturation which attends the chronic uremic state (Teitelbaum et al., 1977 and Russell et al., 1974). It is of interest that our inability quantity of osteoid is in disagreement
to predict the with the study
between
bone
mineral
analysis
Mid
Distal
C. Osteoid
G.
VII)
Correlations
histomorphometry.
surface osteoid surface 0.23’ Non-osteoblastic osteoid surface Osteoclastic resorptive surface 0.22’ Non-osteoclastic resorptive surface 0.25’ Osteoclast 0.20’ Osteoclasts in appos. to trab. bone 0.22’ Osteoclasts not in appos. to trab. bone Osteoid seam width Trab. surf. in appos. to fibrosis Osteoid seam with tetracycline label
D. Osteoblastic
H. (Table
bone
A. Total bone volume B. Relative osteoid vol.
F. Densitometry
43
skeleton
K. L.
M.
Only eL r ~1with 0.05 0.01.
significant
p values
are portrayed.
0.24’ 0.25’ 0.20*
‘p
=
of Malluche et al., (1975). This study, however, includes patients with early renal failure or those It is, therefore, who have never been dialyzed. possible that the predictability of osteomalacia is lost with institution of dialysis. Other investigators have demonstrated correlations between I-PTH and alkaline phosphatase and the features of osteitis fibrosa (Bordier et al., 1975; Duursma et al., 1974; Malluche et al., 1975). As alkaline phosphatase in uremia largely reflects osteoblastic activity, our findings are consistent with the report of Sherrard et al. (1972), that the rate of bone formation is accelerated in those skeletons exhibiting a predominance of osteitis fibrosa. Both total and ionized calcium are predictive of the same spectrum of bone morphology as i-PTH and alkaline phosphatase except in a weaker and negative manner. These correlations exist to a greater degree in non-dialyzed uremic subjects (Bordier et al., 1975; Duursma et al., 1974; Malluche et al., 1975). Furthermore, while Malluche et al. (1975) note an association of calcium with osteoid volume, osteoid surface area and osteoid seam width, these relationships are not present in our dialyzed subjects. This observation is compatible with a previous study (Duursma et al., 1974) which demonstrated a weakening of the association between calcium and bone histomorphometry following the institution of maintenance hemodialysis. In keeping with their relationships to bone histology, an inverse correlation exists between circulating levels of I-PTH and calcium (r = 0.25, p
K.A. Hruska et al.: Predictability
44
of histology
in uremic
skeleton
Radiographic osteosclerosis alkaline phosphatase. is also predictive of PTH induced bone effect, reflecting the observation that increased bone mass occurs in tandem with osteitis fibrosa.
Hruska, K.A., Kopelman, R., Rutherford, W.E., Klahr, S., Slatopolsky, E.: Metabolism of immunoreactive parathyroid hormone in the dog. The role of the kidney and the effects of chronic renal disease. J. C/in. Invest. 56: 39-48, 1975.
It is interesting that we find no relationship of bone densitometry to total bone volume. While this may reflect imprecision of the densitometric techniques (Johnston et al., 19751, it may also mirror the insensitivity of the needle bone biopsy as an indicator of bone mass. In contrast densitometric measurements do weakly relate to some surface based histological features [i.e., osteoblastic osteoid surface, resorptive surfaces and osteoclast number and position]. This may be due to parallel increases in the percentages of trabecular bone surface covered by osteoid and osteoclasts as total bone volume Conchanges during the course of renal failure. sequently, the correlations between these surface based morphometric features and bone densitometry may be reflective of the relationships of these parameters to changing bone mass.
Johnston, C.C., Jr, Smith, A.M., Nance, W.E., and Vevaor. J.: Evaluation of radial bone mass by the photon absorption technique, in Clincal Aspects of Metabolic Bone Disease, edited by France b, Parfitt A.M. and Duncan H. Int Cong Series 270, Amsterdam, Excerpta Medica, 1975, pp. 28-36.
This work was supported by U.S.P.H.S. NIAMDD grants AM-09976, AM-05248 AM-11674. and Division of Research Resources, General Clinical Research Centers Branch, NIH grant 5MOlRR00036-15. Dr. Kevin Martin was supported by a Fellowship Grant from the National Kidney Foundation during the course of this study. Acknowledgements:
Avioli, L.V., and Teitelbaum, S.L.: The renal osteodystrophies in The Kidney, eds B.M., Brenner, and F.C.. Rector. W.B. Saunders, Philadelphia, 1976 pp. 1562. 1591. Barr, A.J., Goodnight, Guide
SAS Institute,
J.G., Sall, J.P., and Helwig, J.P.: SAS 76 Raleigh, North Carolina, 1976. to
Bayers, P.D.: The diagnostic Metabolic
Malluche, H.H., Ritz, E., Kutschera, J.. Krause, G., Werner, E., Gati, A., Seiffert, U., Lange, H.P.: Calcium metabolism and imparied mineralization in various stages of renal insufficiency, in Vitamin D and Problems Related to Uremic Bone Disease, edited by Norman, A.W.. Schaefer, K., Gregoleit, H.G., Herrath, D.V., Ritz, E. New York, Walter de Gruyter, 1975, pp. 513522. Martin, K.J., Hruska, K.A., Lewis, J., Anderson C., and Slatopolsky E.: The renal handlina of oarathvroid hormone. Role of peritubular uptake and ‘glometular filtration. J. C/in. Invest. Invest. 60: 808814, 1977. Mazess, R.B., Cameron, J.R.: Bone Mineral Content in Normal U.S. Whites, in International Conference on Bone Mineral Measurement, edited by Mazess, R.B. Bethesda U.S. Dept of H.E.W. Publication 75: 683, pp. 228-238. Meema, H.E., and Meema, S.: Comparison of microradioscopic and morphometric findings in the hand bones with densitometric findings in the proximal radius in thyrotoxicosis and in renal osteodystrophy.
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Radio/.
7: 88-96, 1972.
Melsen. F.. Mosekilde, L.: Morphometric and dynamic studies of bone changes in hyperthyroidism. Acta. Path. Microbioi. Stand. Sect. A. 85: 141-150, 1977. Melsen, F., and Nielson, H.E.: Osteonecrosis following renal allotransplantation. Acta. Path. Microbial. Stand. Sect. A. 85: 99-104, 1977. Meunier, P., Edouard, C., Courpron, P., and Toussaint, F.: Morphometric analysis of osteoid in iliac trabecular bone. Methodoloav. Cvnamical sianificance of the osteoid parameters. In: Vitamin “D and P&/ems Related to Uremic Bone Disease. AS.. Norman. K.. Schaefer, H.G., Grigoleit, D. von Herrath, and E. Ritz; editors, Walter de Gruyter, 1975, pp. 149-155. Morganstern, S., Kessler, G., Aurbach, G., Flor, R.V., and Klein B.: An automated paranitrophenylphosphate serum alkaline phosphatase procedure for the autoanalyser. C/in. Chem. 11: 876888, 1965. Pierides. A.M., Ellis, H.A.. Simoson. W.. Dewar. J.H.. Ward. M.K., and Kerr,‘D.N.S.: Variable response to long-term la-hydroxycholecalciferol in hemodialysis osteodystrophy. Lancet 1: 1092-1095, 1976. Russell, J.E., Termine, J.D., and Avioli. L.V.: Abnormal bone mineral maturation in the chronic uremic state. J. C/in. invest.
52: 2848-2852, 1973.
Sherrard, D.. Baylink, D., Wergedal, J.: Bone disease in uremia. Trans Amer Sot.-Artif. Intern. Organs. 18: 412-415, 1972. Sherrard, D.J.. Baylink, D.J., Wergedal, J.E., Maloney, N.A.: Quantitative histological studies on the pathogenesis of uremic bone disease. J. C/in. Endocrin. Metab. 39: 119-135. 1974.
Snedecor, G.W., Cochran, W.A.: Statistical Methods. A.mq_els510wa,Iowa State University Press, 1967. pp. Teitelbaum, S.L., Hruska, K.A., Shefber, W., Debnam, J.W., and Nichols, S.H.: Tetracycline fluorescence in uremic and primary hyperparathyroid bone. Kidney Internat 12: 366, 1977. Received: January 15, 1978. Revised: May 15, 1978. Accepted: May, 25, 1978.
Bone
Dis.
& Rel. Res.
Metabolic Bone Disease 8 Related Research
1, 39-44 (1978)
@ by S.N.P.M.D. (Paris 1979)
The predictability of uremic bone
of the histological features disease hy non-invasive techniques
KEITH A. HRUSKA, STEVEN L. TEITELBAUM, ROBERT KOPELMAN, CATHERINE A. RICHARDSON, JAMES DEBMAN, KEVIN MARTIN, AND EDUARDO SLATOPOLSKY Renal Division, Department of Medicine, Washington University, Division of Bone and Mineral Metabolism, The Jewish Hospital St. Louis, Missouri 63110.
Department of St. Louis,
of Pathology Washington,
Address
Med.
Div.
for correspondance
and reprints:
Keith
A. Hruska,
Abstract Forty-six uremic patients on chronic hemodialysis underwent bone biopsy to ascertain the relationships of serum biochemistry, radiographic analysis, and bone mineral analysis to bone histomorphometry. Circulating levels of immunoreactive parathyroid hormone and alkaline phosphatase, as well as radiographically apparent subperiosteal resorption, are most predictive of osteitis fibrosa. Bone densitometry correlated poorly with some parameters of osteitis fibrosa and not with histologically measured bone volume. None of the clinical parameters tested are predictive of osteomalacia. These findings underscore the necessity of bone biopsy to accurately assess the chronically uremic skeleton.
Key Words: Hyperparathyroidism Bone Biopsy metry.
- Serum
Biochemistry
- Osteomalacia - Bone Morpho-
Introduction Renal osteodystrophy is a generic term which a host of skeletal abnormalities encompasses The morphological attending chronic renal failure. alterations include combinations of osteitis fibrosa, osteomalacia, osteosclerosis, and osteopenia (Jowsey et al., 1969; Duursma et al., 1972; Bordier et al., 1975; Duursma et al., 1974; Sherrard et al., 1972; Malluche et al., 1975). In recent years, significant advances have occurred in the treatment of renal The potential complications of some osteodystrophy. of these therapeutic modalities have underscored the necessity of exact histological characterization of the skeletal lesion (Pierides et al., 1976). While the introduction of simple methods of obtaining trocar biopsies of the ileum, and the development of techniques of preparing well preserved, non-decalcified thin histological sections of bone have made this delineation possible, these procedures are not widely available. We have, therefore, undertaken a study to determine if the histology of the uremic skeleton is predictable by the use of readily available, non-invasive clinical techniques. These results demonstrate that high levels of circulating immunoreactive parathyroid hormone (IPTH), alkaline phosphatase and radiographic evidence of subperiosteal
Int.
Renal
PHILIP MILLER.
and Laboratory Medicine, and University School of Medicine,
499 S Euclid
St. Louis,
MO. 63110.
resorption reflect the presence of osteitis fibrosa. On the other hand, the quantity of osteoid. and hence the degree of osteomalacia are not predictable by non-invasive techniques.
Materials
and Methods
studied consisted of 111 patients, all of whom had end-stage renal disease treated by chronic hemodialysis at the Chromalloy American Kidhey Center, St. Louis, Missouri, during the period of June, 1974 to January, 1976. Forty-six (41%) of the total group were selected to undergo bone biopsy on the basis of affirmative consent and an attempt to closely match the clinical findings of the patient population as a whole (Table 1). All biopsied patients were older than twenty years of age. Twelve (26%) were over 50 years of age, and 21 were female. The mean duration of dialysis ranged from five to ninety-six months, with a mean of thirtyseven months. Twenty-nine patients were treated at home, and seventeen were on center dialysis. None of the patients had undergone previous renal transplantation, although three had undergone nephrectomy in preparation for transplantation. None of the patients had recieved corticosteroid or anticonvulsant therapy while on chronic hemodialysis. ~
The population
Dialysis was performed for 5-7 hours, three times a week, using Travenol coil dialyzers (Model U2. 100 or 1451, and the Travenol EJSL 120 bath containing 130 mEq/L sodium,
Table I. Clinical
diagnoses
of renal
disease
in the
study
population.
Diagnosis
Biopsied
ia
Chronic Glomerulonephritis Acute Glomerulonephritis’ Nephrosclerosis Chronic Pyelonephritis Tuberous Sclerosis Diabetes Malignant Hypertension Alports Syndrome Interstitial Nephritis Polycystic Kid.ney Disease Nephrocalcinosis
1
6 10
46 ‘less
than
6 months
disease
course.
Total Dialysis Pooulation 47 2 15 15 2 4 11 2 2 10
111
40
K.A.
2 mEq/L potassium, 3.25 mEq/L calcium, 1.5 mEq/L maanesium. 37 mEa/L acetate. 0.25 a/dl dextrose. All patyents ingested ph’osphate binders t; maintain normal serum phosphorus. Supplemental elemental calcium, sufficient to provide a daily intake Of 1.0-1.5 grams was administered except during periods of hyperphosphatemia. Thirteen biopsied patients had been taking 25,000-100,000 units of vitamin DZ per day for variable periods at some time during their time on chronic hemodialysis. Since this treatment had no significant effect on the relationships between clinical and histological measurements, these patients were not segregated from the total study population for this report.
Biochekical
Determinations
Blood levels of total calcium, phophorus, magnesium and creatinine were determined every six to eight weeks in all patients as previously descritied (Hruska-et al., 1975; Chase et al.. 1974). Alkaline prosphatase was measured every sixteen to twenty weeks by the method of Morganstern et al. (1965). Plasma ionized calcium was examined every twelve fo fifteen weeks using a flowthrough membrane electrode (Orion Research, Cambridge, Massachusetts). lmmunoreactive parathyroid hormone (i-PTH) was determined at the same time employing the CH9 antiserum (Hruska et al., 1975; Chase et al., 1974). The determinants of binding to this antiserum are in the carboxyl terminal portion of the PTH molecule. Consequently, the immunoreactive forms detected include native PTH and carboxvl terminal fragments. These _.__.. fragments are largely eliminated by the kidney and are thus _..-- retained ~~ .~ in chronic renal failure (Martin et al.. 1977; Freitag et al., 1978). The range of I-PTi-l of the group was 9-940 plEq/ml (normal 2-10). All patients, except two who had been parathyroidectomized, had elevated I-PTH levels.
Bone
Histomorphometry
A[[ patients received 750 mg of tetracycline per day orally for three days prior to biopsy. Transiliac bone biopsy having a 0.5 cm internal was performed with a trocar diameter. The specimens, which included both cortices and intervening trabeculae. were fixed in neutral buffered formalin after which they were embeddad, non-decalcified, in methylmethacrylate and cut in sections 5.0 pm thick on a Jung Model K Sledge Microtome (Jung Instruments, Heidelberg, Germany). The entire trabecular area of two sections taken from approximately one-third and one-half the thickness of the core, and stained by a modification of the Goldner technique, was evaluated histometrically using a Zeiss II Integrating Eyepiece at 200X magnification (Bayers, 1977). The tetracycline-based fluorescent parameter was quantitated in the same fashion using two unstained IO pm thick sections also taken from different levels of the specimen. The following histological features were quantitated: a) percent total bone volume, or the percentage of trabecular bone covered by osteoid not b) percent relative osteoid volume; or the percentage of trabecular bone matrix which is unmineralized: c) percent trabecular surface covered by osteoid; d) percent osteoblastic osteoid surface, or the percentage of trabecular bone covered by osteoid lined by typical, plump osteoblasts: e) percent non-osteoblastic osteoid surface, of the percentage of trabecular bone covered by osteoid not lined by typical, plump osteoblasts: f) percent osteoclastic resorptive surface, or the percentage of trabecular surface characterized by resorptive bays (Howships’s lacunae] in apposition to osteoclasts; g) percent nonosteoclastic resorptive bays not in apposition to osteoclasts; h) number of osteoclasts/mmz of cancellous space: i) number of osteoclasts/mmz of cancellous space in apposition to trabecular bone surface; j) number of osteoclasts/mm2 of cancellous space not in apposition to trabecular bone surface; k) mean osteoid seam width. This is a derived value obtained by dividing the osteoid volume by its absolute linear extent; I) percent of trabecular surface in apposition to marrow fibrosis; m) the percentage of osteoid seam-mineralized bone interface labeled by tetracycline fluorescence.
Hruska
et al.:
Predictability
of
histology
in uremic
skeleton
These results were compared to those obtained from samples acquired at autopsy from patients suffering sudden death. The controls included eleven males and six females at a mean age of 45.8 +- 20.6 (S.D.) years. The percentage of osteoid seam mineralized bone interface assuming a tetracycline label in our uremic patients was compared to the normal bone biopsies reported by Melsen and Nielsen, 1977. Radiographic (Table
Analysis
II)
All radiologic grading was performed without clinical or histological information available to the observer. The radiographic studies included views of the skull, chest, shoulders, hands, lumbar spine, abdomen and pelvis. For purposes of statistical correlation, resorptive changes were graded for severity and distribution. The hand films obtained for this purpose at the time of iliac crest biopsy were studied by the magnification technique of Meema and Meema, 1972. We also graded random asymmetric ectopic soft tissue calcifications noted especially in the hands and wrists, but also about the shoulders, elbows, hips and knees. Since stress, traumatic and pathologic fractures could not be definitely differentiated from Looser’s zones, these were all considered as fractures. Finally, vascular calcifications, especially involving arteries of the hands and pelvis, were quantitated. Bone
Mineral
Determinations
Bone mineral analysis was performed every sixteen weeks on the mid distal radii of all patients using the Norland Cameron Bone Mineral Analyzer (Cameron and Sorenson, 1963; Cameron et al., 1968). A standard apparatus for repositioning das employed. The ratio of bone
mineral content (g/cm) to bone width (cm) was determined. The derived quantity, BM/BW (g/cm2) was compared to data obtained from age and sex matched normal subjects (Mazess and Cameron, 1975). Statistical
Methods
The results of the various studies and the information abstracted from the charts were recorded on specially designed forms, keypunched and entered into a computerized data base using the SAS statistical analysis and data base management system [Barr et al., 1976). Many of the variables subjected to anlaysis were distributed in a distinctly non-normal fashion, a result expected
from the pathological nature of the patient population and the nature of the variables themselves. This non-normality precludes the use of the standard product moment correlation coefficient (r) for assessing the strength of the association in this group of patients. Rather than examining each variable in order to select an appropriate transformation (log, arc sin, or reciprocal), Kendall’s Tau b test which is a non-parametric measure of association was employed (Snedecor and Cochran, 1967). Scatter plots of relationships were also produced and examined to facilitate interpretation of potentially afalse positive* correlation coefficients in the absence of estimated parametric functional relations between the variables. Significance levels were calculated using standard formulae and are presented for reference as the probability that the value of the correlation coefficients (r) were greater than zero.
Results No differences exist between the levels of blood biochemical determinants of the biopsied patients measured at the time of biopsy or during the threemonth period prior to biopsy, when compared to the entire dialysis population (Table III). Furthermore, the biopsies taken from the uremic patients exhibit the classical changes of renal osteodystrophy (Table IV]. There is an abundance of osteoid, osteoclasts, osteoblasts and peritrabecular marrow fi-
K.A.
Hruska
et al.:
Predictability
Table II. The grading
Radiographic
Severity
of
Distribution
of
histology
in uremic
used for analysis of the radiographic
system
Abnormal
Findings
Demineralization
Ectopic
Criteria
1 2 3 4
borderline mild moderate severe
1 2 3 4
subperiosteal resorption base of phalanx subperiosteal resorption midshaft of phalanx sclerosis of vertebral bodies sclerosis beyond vertebral column
1 2 3 4
none slight moderate mineralization
1
none definite < 2.5 cm dia., one site more than one site, all < 2.5 cm one or more, > 2.5 cm
2 3 4
Calcification
1 Fractures
(Looser’s
Zones)
: 4
and Histomorphometric
Parameters
bone interface which assumes a tetracycline also correlated with these two biochemical minants.
LPTH and alkaline phosphatase are the biochemical tests most predictive of the presence of osteitis fibrosa, viz. (dl percent trabecular surface covered by osteoblastic osteoid, (f) percent trabecular surface containing osteoclasts, (h) the number of osteoclasts/mm’ cancellous space, osteoclasts on (il and
Radiographic
Table Ill. Mean population.
serum
alterations
minerals,
also
iPTH plEq/ml
Parameters
As would be expected, radiographically determined osteosclerosis and demineralization respectively,
correlated
iPTH and alkaline
and Histomorphometric
label deter-
(Table VI)
off (j) trabecular surfaces and the (I] ‘percent to marrow fibrosis. trabecular surface in apposition morphological
tissue
Increased relative osteoid volume and percent osteoid surface, which are the histological features most characteristic of osteomalacia (Avioli and Teitelbaum. 1976), are not predictable by biochemical evaluation. However, the width of the osteoid seams correlated with both I-PTH and alkaline phosphatase even though this histological feature was within our normal range. Furthermore, the percentage of osteoid-mineralized
(Table VI
The same
to soft
negatively and less significantly with both ionized and total calcium. Phosphorous and magnesium are even less predictive of the histological lesion.
brosis. A marked deficit in the percentage of osteoid seam-mineralized bone interface which assumes a tetracycline label is also apparent. Interestingly, the increase in osteoid present in the uremic biopsies is due to an increase in the percent of trabecular bone surface covered by osteoid and not to augmentation of the mean osteoid seam width.
Biochemical
equal
single arterial plaque scattered noncontinuous plaques longer calcified arterial segments uninterrupted arterial wall calcification
32 4
Calcification
normal
questionable hairline fracture one definite fracture two-four fractures more than four fractures
1 Vascular
findings.
Grade
Parameter
Osteodystrophy
of
41
skeleton
phosphatase
Calcium mgldl
Ca++ mg/dl
determination
Alk.
in biopsied
Phos. I.U.
patients
Phos. mgldl
and in total
Magnesium mg/dl
patient
Creat. mg/dl
ti SD N
327 280 41
10.0 1.2 45
4.4 0.6 41
112 154 45
5.1 1.3 45
2.8 0.3 41
12.2 3.2 45
Biopsied patients M value during 3 months prior to biopsy
G SD N
316 278 80
9.9 1.4 138
4.3 0.7 80
116 152 96
5.1 1.3 138
2.8 0.4 80
12.0 3.3 138
Mean all determinations of entire dialysis population
i SD N
274 281 468
9.9 1.2 1179
4.3 0.7 396
116 136 1194
4.8 11841.8
0”:: 396
12.0 4.3 1164
Biopsied at time
patients of biopsy
IPTH. immunoreactive serum phosphorus minations.
parathyrold hormone Great., serum creatinine
Ca++, ionlzed calcium M = mean - SD =
Alk.
Phos.,
alkaline -
standard deviation
Phos., phosphatase N = number of deter.
42
K.A.
Table IV. Mean
-t
SD of histomorphometric
Histological
determinations
Determined
Table
by non-paired
V. Correlation
Histomorphometric
Mean 21.9 2.0 12.6 1 .o 11.6 0.162 2.2 0.112 0.077 0.035 0 86.6
VI.
between
tests
done
coefficients
Total bone volume Relative osteoid vol. Osteoid surface Osteoblastic osteoid surface Non-osteoblastic osteoid surface Osteoclastic resorptive surface Non-osteoclastic resorptive surface Osteoclast Osteoclasts in appos. to trab. bone Osteoclasts not in appos. to trab. bone Osteoid seam width Trab. surf. in appos. to fibrosis Osteoid seam with tetracycline label r’s with
significant
p values
histology
Mean 22.7 13.4 71.9 5.4 66.5 1.9 9.7 1.5 1.4 0.1 8.0 13.9 51.4
in uremic
and a normal
Hemodialysis
and quantitative
bone
Alkaline Phosphatase
between SubpeResorpt.
Histological Parameters
Only
on serum
Determination
coefficients with significant NS = not significant.
Correlation
on hemodialysis
of
st & i_ & ++++++++ t t
control
patients
skeleton
population.
Significance of differences*
SD 10.3 8.6 13.9 5.0 16 1.8 5.4 1.7 1.6 0.2 6.1 20 30.8
N.S. < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.05 N.S. P < 0.001 P < 0.001
P P P P P P P P P
t test
NS
Total bone volume Relative osteoid volume Osteoid surface Osteoblastic osteoid surface Non-osteoblastic osteoid surface Osteoclastic resorptive surface Non-osteoclastic resorptive surface HG. Osteoclast I.’ Osteoclasts in apposition to trabecular bone not in apposition to J. Osteoclasts trabecular bone K. Osteoid seam width L. Trabecular surface in apposition to fibrosis M. cl0 Osteoid seam with tetracycline label
Table
Predictability
c SD f a.4 -c 2.3 + 13.9 + 1.7 - 12.9 2 0.230 +- 1.5 f 0.121 +- 0.108 + 0.049 c 6.1 f 0 t 22.1
lo.8
A. B. C. D. E. F.
Only correlation 0.005 - 0.0001 -
al.:
Normals
student’s
coefficients
et
of patients
parameter
Total bone volume Relative osteoid volume Osteoid surface Osteoblastic osteoid surface Non-osteoblastic osteoid surface Osteoclastic resorptive surface Non osteoblastic resorptive surface Osteoclast Osteoclasts in apposition to trabecular bone Osteoclasts not in apposition to trabecular bone Osteoid seam width Trabecular surface in apposition to fibrosis O/O Osteoid seam with tetracycline label l
Hruska
histomorphometry
Calcium
NS
Ii:
NS
E
I%
NS
0.62t NS 0.51t
0.3at NS 0.37t
-0.23’ NS -0.28+
0.33’ 0.49t
0.25’ 0.3at
-zst
0.26’ NS 0.27+
0.49t
0.37t
-0.32t
0.30t
0.49t 0.23” 0.50+ 0.42t
095t 0.36t 0.40+ 0.39t
-0.34t NS
!Z
0.36+ -0.25’
0.24’ NS
p values
radiographic
are
portrayed.
grading
Endosteal Cortical Resorpt. Striations
l
=
and bone Distal Clav. Resorpt.
0.05
0.27’
+
=
0.01
- 0.005 -
Osteosclerosis
Demineralization
Fractures
ACr;g;il
cation
cation
0.33+
0.32+
0.33+
0.24’
0.4ot
-0.34t
0.24’
0.33+
0.26.
0.27’
0.31f
portrayed.
*p =
0.05 -
..
0.26.
0.32+ 0.32+
0.26’
=
W&pie. .
0.24’
0.35+
t
histomorphometry.
0.43t
0.32+ - 0.25, 0.35t
- 0.01 -
E
0.01 - +p = 0.01 -
0.005 - tp
= 0.005 -
0.0001.
K.A. Hruska et al.: Predictability
of histology
in uremic
Similar to the levels of i-PTH and alkaline phosphate, the degrees of osteosclerosis and particularly, subperiosteal resorption, correlate with the magniNo radiographic feature tude of oseitis fibrosa. relates to relative osteoid volume or percent osteoid surface. Again, in conjunction with I-PTH and alkaline phosphatase, the degree of subperiosteal resorption relates to the percent of osteoid seam with a tetracycline label.
Table VII. and
and Histomorphometry
E.
1.
J. The mean value of the biopsied patients’ mid and distal shaft mineral content/width ratio respectively is 0.65 2 0.12 (S.D.) and 0.44 -r- 0.10. These values are more than two standard deviations below that of age and sex matched controls (Mazess and Cameron, 1975). While there is progressive loss of mid and distal shaft mineral content/bone width with duration of dialysis (r = 0,25, p <.OOl, densitometric measurements correlate poorly with the morphological features of renal osteodystrophy
(Tabel VII). Discussion The results of this study indicate
that the magnitude of osteitis fibrosa is reasonably predictable in the dialyzed uremic skeleton by non-invasive parameters, specifically I-PTH, alkaline phosphatase and radiographically apparent subperiosteal resorption. On the other hand, the presence of excess osteoid can be evaluated only by bone biopsy. As uremic patients most often have combinations of osteitis fibrosa and osteomalacia, these data underscore the necessity of histological confirmation of the skeletal lesion prior to therapy. Furthermore, if treatment is directed toward amelioration of osteomalacia, its effectiveness can only be appreciated by bone biopsy. Although the presence of increased quantities Of osteoid is essential to the diagnosis of osteomalacia, this morphological feature may exist in the absence of a mineralization defect. Specifically, osteoid may be augmented in states of accelerated organic matrix synthesis such as hyperthyroidism (Melsen and Mosekilde, 1977). The distinction between hyperosteoidosis due to a mineralization defect and that secondary to accelerated matrix synthesis is best made by the use of time-spaced (double) fluorescent tetracycline labels (Meunier et al., 1975). As in our group of patients, however, the presence of osteomalacia may also be established by a paucity of osteoid seams which assume a fluorescent label (Bordier and Tun Chot, 1972). The one feature of osteomalacia which is reflected biochemically and radiographically is percent osteoid seam assuming a tetracycline label. However, as demonstrated in this laboratory, this parameter may be normal in uremic patients despite the presence of a mineralization defect (i.e., osteomalacia) demonstrable by other morphological measurements (Teitelbaum et al., 1977). Consequently, the relationship between I-PTH and the percent osteoid seam assuming a tetracycline label may reflect delayed mineral maturation which attends the chronic uremic state (Teitelbaum et al., 1977 and Russell et al., 1974). It is of interest that our inability quantity of osteoid is in disagreement
to predict the with the study
between
bone
mineral
analysis
Mid
Distal
C. Osteoid
G.
VII)
Correlations
histomorphometry.
surface osteoid surface 0.23’ Non-osteoblastic osteoid surface Osteoclastic resorptive surface 0.22’ Non-osteoclastic resorptive surface 0.25’ Osteoclast 0.20’ Osteoclasts in appos. to trab. bone 0.22’ Osteoclasts not in appos. to trab. bone Osteoid seam width Trab. surf. in appos. to fibrosis Osteoid seam with tetracycline label
D. Osteoblastic
H. (Table
bone
A. Total bone volume B. Relative osteoid vol.
F. Densitometry
43
skeleton
K. L.
M.
Only eL r ~1with 0.05 0.01.
significant
p values
are portrayed.
0.24’ 0.25’ 0.20*
‘p
=
of Malluche et al., (1975). This study, however, includes patients with early renal failure or those It is, therefore, who have never been dialyzed. possible that the predictability of osteomalacia is lost with institution of dialysis. Other investigators have demonstrated correlations between I-PTH and alkaline phosphatase and the features of osteitis fibrosa (Bordier et al., 1975; Duursma et al., 1974; Malluche et al., 1975). As alkaline phosphatase in uremia largely reflects osteoblastic activity, our findings are consistent with the report of Sherrard et al. (1972), that the rate of bone formation is accelerated in those skeletons exhibiting a predominance of osteitis fibrosa. Both total and ionized calcium are predictive of the same spectrum of bone morphology as i-PTH and alkaline phosphatase except in a weaker and negative manner. These correlations exist to a greater degree in non-dialyzed uremic subjects (Bordier et al., 1975; Duursma et al., 1974; Malluche et al., 1975). Furthermore, while Malluche et al. (1975) note an association of calcium with osteoid volume, osteoid surface area and osteoid seam width, these relationships are not present in our dialyzed subjects. This observation is compatible with a previous study (Duursma et al., 1974) which demonstrated a weakening of the association between calcium and bone histomorphometry following the institution of maintenance hemodialysis. In keeping with their relationships to bone histology, an inverse correlation exists between circulating levels of I-PTH and calcium (r = 0.25, p
K.A. Hruska et al.: Predictability
44
of histology
in uremic
skeleton
Radiographic osteosclerosis alkaline phosphatase. is also predictive of PTH induced bone effect, reflecting the observation that increased bone mass occurs in tandem with osteitis fibrosa.
Hruska, K.A., Kopelman, R., Rutherford, W.E., Klahr, S., Slatopolsky, E.: Metabolism of immunoreactive parathyroid hormone in the dog. The role of the kidney and the effects of chronic renal disease. J. C/in. Invest. 56: 39-48, 1975.
It is interesting that we find no relationship of bone densitometry to total bone volume. While this may reflect imprecision of the densitometric techniques (Johnston et al., 19751, it may also mirror the insensitivity of the needle bone biopsy as an indicator of bone mass. In contrast densitometric measurements do weakly relate to some surface based histological features [i.e., osteoblastic osteoid surface, resorptive surfaces and osteoclast number and position]. This may be due to parallel increases in the percentages of trabecular bone surface covered by osteoid and osteoclasts as total bone volume Conchanges during the course of renal failure. sequently, the correlations between these surface based morphometric features and bone densitometry may be reflective of the relationships of these parameters to changing bone mass.
Johnston, C.C., Jr, Smith, A.M., Nance, W.E., and Vevaor. J.: Evaluation of radial bone mass by the photon absorption technique, in Clincal Aspects of Metabolic Bone Disease, edited by France b, Parfitt A.M. and Duncan H. Int Cong Series 270, Amsterdam, Excerpta Medica, 1975, pp. 28-36.
This work was supported by U.S.P.H.S. NIAMDD grants AM-09976, AM-05248 AM-11674. and Division of Research Resources, General Clinical Research Centers Branch, NIH grant 5MOlRR00036-15. Dr. Kevin Martin was supported by a Fellowship Grant from the National Kidney Foundation during the course of this study. Acknowledgements:
Avioli, L.V., and Teitelbaum, S.L.: The renal osteodystrophies in The Kidney, eds B.M., Brenner, and F.C.. Rector. W.B. Saunders, Philadelphia, 1976 pp. 1562. 1591. Barr, A.J., Goodnight, Guide
SAS Institute,
J.G., Sall, J.P., and Helwig, J.P.: SAS 76 Raleigh, North Carolina, 1976. to
Bayers, P.D.: The diagnostic Metabolic
Malluche, H.H., Ritz, E., Kutschera, J.. Krause, G., Werner, E., Gati, A., Seiffert, U., Lange, H.P.: Calcium metabolism and imparied mineralization in various stages of renal insufficiency, in Vitamin D and Problems Related to Uremic Bone Disease, edited by Norman, A.W.. Schaefer, K., Gregoleit, H.G., Herrath, D.V., Ritz, E. New York, Walter de Gruyter, 1975, pp. 513522. Martin, K.J., Hruska, K.A., Lewis, J., Anderson C., and Slatopolsky E.: The renal handlina of oarathvroid hormone. Role of peritubular uptake and ‘glometular filtration. J. C/in. Invest. Invest. 60: 808814, 1977. Mazess, R.B., Cameron, J.R.: Bone Mineral Content in Normal U.S. Whites, in International Conference on Bone Mineral Measurement, edited by Mazess, R.B. Bethesda U.S. Dept of H.E.W. Publication 75: 683, pp. 228-238. Meema, H.E., and Meema, S.: Comparison of microradioscopic and morphometric findings in the hand bones with densitometric findings in the proximal radius in thyrotoxicosis and in renal osteodystrophy.
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