Spinal osteoporosis in men

Boneond Mineral,

341

5 (1989) 347-357

Ek.evier

BAM 00175

Spinal osteoporosis in men

R.M. Francis’, M. Peacock’, D.H. Marshall), A. Horsman4 and

J.E. Aaron’

(Received 19 November 19g7) (Accept.?6 1 August 1988,

In be&by men, metacarpaland femoralconicalanaitowl area. bonewtumc. oneoid surfaces.seam and trabecularwidth, plasmadihydroepiandrmtemneal: estrone,and radiocalciumabsorptionfell with age,whereaserodedsuriaees.lrabecularnumber.urine hydroxyprolineandcakiundcreatitie raties, plasmaalkaline phosphatare,estradiol.androstenedione, cnnisoland ~e~toswoncremainedccmstantwith age. As comparedwith hcakty mm, menwith primaryosteopmosirbadreducedfcmorillconical area/total area (P < 0.;;;. a.: :ine*-& e--z& (P < O.COl) and in seventherewasa hiswry of facarm or femoral fracture.On iliac crestbiopsy,bonevolume(P < O.aOl) and trabeculsrnumber(P < 0.01) were decreased.plarma alkaline phaphatase(P < 0.02) was increasedbut wine hydroxyprolineand calcium excretionwere not significantlyraised.Calcium balancewas negativedw to failure of abwrption to matchurinarycalciumlossandradiocalciumabsorption(P ( 0.01) andplasma1,ZSdihydroxyvitaminD (P c 0.05) were reduced.

Key wards: Osteoporosis; Men; Bonehistology;Biochemistry:Age

with age in both men and women [1,2] and although the incidence of osteoporotic fractures is lower in men, the 10s~of bone in both sexes is accon~paBone loss occurs

Correspondence to: Munro peacock.M.D., GeneralClinical ResearchCenter, IndianaUniversiiyHmpital. 926WestMichiganStreet.IndianapaSs.IN 46223.USA, Ot69&009~89~SO~.SO~ 19S9ElsevierSciencePublishersB.V. (BiomedicalDivision)

348 nied by an increased risk of fracture of the forearm, vertebral body and femoral neck [2,3]. In healthy women, bone loss becomes obvious at the menopause and histological and biochemical studies indicate that it is accompanied by a rise in bone resorption [4,5]. Factors other than estrogen deficiency which contribute to bone loss include decreased dietary calcium intake, reduced physical activity, low body weight and cigarette smoking 16-91. In addition a decrease in plasma adrenal androgens after the age of 50 [lo] and in calcium absorption after the age of 66 have been implicated [Ill. Women with crush fractures due to primary osteoporosis have lower calcium absorption [12,13] and plasma estrone and androstenedione concentrations [14] compared with age-matched subjects without fractures, indicating that calcium malabsorption and poor estrogenisation are risk factors for osteoporosis. In contrast to women, little has been published on osteoporosis in men [15-171. In order to investigate the factors involved in age-related bone loss in men and the pathogenesis of crush fracture. we have studied age-related changes in trabecular and cortical bone mass, biochemical and histological indices of bone turnover, plasma sex steroids and calcium absorption in healthy men and in men presenting with two or more vertebral crush fractures due to primary osteoporosis.

Patients and Methods

The changes with age in bone mass, biochemical indices of bone turnover, plasma sex s:eroids and calcium absorption were assessed from cross-sectional investigations of men aged between 20 and 90. They were recruited from hospital staff or from a medical out-patient clinic which they were attending either for investigation of a minor complamt or for follow-up several weeks after an acute illness known not to affect calcium metabolism. Each individual gave informed consent for investigation. The age-related changes in bone histomorphometry were obtained from autopsy samples of the iliac crest taken from men dying after acute illnesses or from disorders not known to affect calcium metabolism. Details of the numbers and age range of the control subjects for each variable are given in Table 1.

osteoporotic patients Studies were carried out on 94 men referred consecutively to a bone clinic who were found on radiographs to have two or more vertebral crush fractures. After obtaining a medical history and performing a physical examination, all patients were investigated to exclude secondary osteoporosis. Methods Radiographs of the right hand, left femur and lateral thoracic and lumbar spine were obtained. The metacarpal cortical area/total area (MCAfTA) and femoral cortical ares/total area (FCATA) were measured [18]. The trabectdar pattern of the femoral neck was graded from 1 to 6 by two observers independently using the

349 method of Singh [19], in which the severity of the osteoporosis increases as the grade decreases. Each of the thoracic and lumbar vertebrae were examined morphometrically and given a score of 1 if wedged and 2 if collapsed, and a total spine score was calculated for each patient 1201. Transiliac bone biopsies were obtained in all patients using a Bordier trephine, and after embedding in methyl methacrylate, lO+m sections were cut with a Jung heavy duty microtome [Zl]. In the normal subjects some biopsies were obtained by wedge resection but as previously described were shown not to give data different from transiliac biopsies 1221. Quantitative measurements of the cancellous bone were made on four fields on each of 16 sections using a Zeiss No. 1 integrating eyepiece. Cancellous bone volume was measured by point counting, and osteoid and eroded surfaces by line-intercept methods (211. The percentage of osteoid surfaces with a mineralization front was estimated by intercept counting [21]. Mean wteoid seam width was determined by direct measurement using a graduated eyepiece graticule and a magnification of x 500. The trabecular architecture was investigated by measurement of trabecular number per field and width (221.The mineral apposition rate was calculated for both cortical and cancellous bone using an in viva tetracycline label and in vitro xylenol orange stain 1231. Blood and urine were collected after an overnight fast. Plasma calcium, phosphate and creatinine concentrations, alkaline phosphatase activity, and urine calcium (Ca) and creatinine (0) concentrations were measured using standard techniques. Urine hydroxyproline (OHPr) was estimated using a resin-catalyscd hydrolysis and an automated calorimetric procedure [%4]. Calcium absorption was measured in the fasting state by estimating plasma radioactivity one hour after the oral administration of 5&i “Ca together with 0.5 mmol calcium chloride carrier in 250 ml deionized water. The fractional rate of absorption of radiocalcium was calculated using the formula: radiocalcium absorption (fraction of dose/hour) = 1.17f+ 2.54 $ wheref= % administereddose/litre at 1 hour x body weight (kg) x 0.0015 [25]. In ten patients and their aged-matched controls, plasma 25-hydroxyvitamin D (25(OH)D), l&dihydroxyvitamin D (1,25(OH),D) and parathyroid hormone (PTH) concentrations were measured at the same time as calcium absorption. After preliminary extraction with ether and separation by high pressure liquid chmmatography [26] plasma 25(OH)D was determined by a radiocompetitive proteinbinding assay [U], and plasma 1,25(OH),D by radioimmunoassay [28]. Plasma PTH was measured by C-terminal radioimmunoassay [29]. Calcium balance studies were performed in 16 patients on a constant calcium diet (intake 16-32 mmol/day) which approximated to their usual dietary intake of calcium using polyethylene glycol 500 mg three times daily as a non-absorbable faecal marker. After a week’s equilibration, seven consecutive daily balances were performed as described previously [XI]. Plasma cortisol, dehydroepiandrosterone (DHEA), androstenedione, estrone (E,), testosterone and estradiol (E*) concentrations were measured by radioimmunoassay.

350 The relationship in the control subjects between each variable and age was determined by regression analysis. For each variable a patient was matched with a control by age, with the maximum

difference

in age being three years. The statistical

significance of differences between osteoporotic patients and age-matched controls was calculated using Student’s t test for paired observations.

Concrolsubjeca (Fig. 1 and Table 1) There was a loss of both cortical and cancellous bone with age as assessed by a reduction in MCA/TA,

FCAtTA

and bone volume. This was associated with a reduc-

tion in osteoid surfaces, osteoid seam width eroded surfaces, trabecular and Ca/Cr DHEA

did not change with

and estrone concentrations

sol. androstenedione.

and trahecular

width

(Fig.

1). but

number. plasma alkaline phosphatase, urine OHPR/Cr age. Radiocalcium

absorption

also decreased significantly

testosterone andestradiol

levelsdid not.

[ll]

and plasma

with age but corti-

351 Table 1 The mean + SEM of the variables

measured and the age range in the control sub-

_

MCA/rA

209

0.730 f o.co6

PCNr.4

66

0.810 * o.w6

50

5.42 * 0.12 21.1*0.6% 9.0 * 0.6% 6.1 f 0.3% 9.3 * 0.2qll 134 f 58m 167f5cm-’ 8.2 f 0.3 KA units 0.011 * O.Wl (molar) Il.*, + 0.01 (molar) 197.0 k 8.9 pmo”nd 95.0 * 8.1 pm&l 0.6 f 0.6 nmobl 15.8 c I .3 nmoUl 354.9 * 14.7 nmoul 19.3?0.8nmoVl

Singbgrade Cancellous bone volume Osteoid surfaces Eroded rurtacess Seam width Trabecularwidth Trabeculrrnumber Plasma alkaline phasphatase Urine OHPd0 Urine WCr Plasma estmne Plasma sstradiol Plasma andrortendione Plasma DHEA Plasma conisol Plasmatestatero”e Radiocalcium abrorprion’ (fraction absorbedlb)

93

w 90 59 4”

40 95 103 102 6S 56 69 65 66 73 63

0.56 * 0.03

Range

Median

20-79 w-79 IL-86 21-89 Z-89 21-89 20-96 20-96 20-96 20-86 20-N 20-86 24-73 24-66 ?A-73 25-73 24-73 24-73

65 55 56 55 55 55 58 53 53 52 52 52 48 48 49 49 50 49

20-m

56

Table 2 Classification

and age range

of 94 men presenting

with

spinal osteoporosis

Number

Primary Secondary Steroid therapy Neoplasdc disease Gastric surgery Hypogonadism Anticonwlsant therapy Osteogenesisimperlccta Homocystinuria ImmobitiMion _) Steatorrhoea Combinedcauses Total

40 15 7

29-81 SO-67 60-76

4 4 2

10

s4

32-79 32-39 22-47 32-32 76 64 39-74 22-81

60 57 67 56 33 36 32 76 64 56 57

352 Table 3 Radiographic data (mean + SEM) in men with primary osteoporosis and agematched control subjects (n = number of pairs) &t-A Controlsubjects Rimuyoatcopomtirr

(n = 27)

0.741 t 0.014 0.737 f 0.017 N.S.

FC.4,TA (n = 29)

Sin@ grade(a = 27)

0.801* 0.010 0.762 * 0.014 P
5.59 * 0.10 2.83 + 0.16 P c 0.001

Osteoporotic pntients

Of the 94 osteopomtic men with vertebral crush frachlres 40 had primary (idiopathic) osteoporosis and 54 had osteopomsis secondary to either steroid therapy, neoplastic disease, gastric surgery, hypogonadism, anticonvulsants. osteogenesis imperfecta, homocystinuria, immobilization or steatorrhoea (Table 2). Of the ten patients with more than one mndition known to be associated with osteoporosis, five had undergone gastric surgery, five were on anticotwtdsant therapy, five had alcoholism, hw were on steroid therapy, two had hypogonadism and one had malignant disease (Table 2). Altb~ugb aimholism did not appai to cause osteoporosis by itself, alcoholism occurred in five patients who had another disease causing osteopo rosis. The patients with secondary osteoparosis tended to be younger at presentation than those with primary osteoporosis and thii was particularly apparent with anticonvulsant therapy, osteogenesis imperfecta and homocystinwia (Table 2). Of the 11 osteopomtic men presenting under the age of 40, only one had primary OSteoporosis. All patients with primary osteoporosis had a spine score of four or above. A fracture history revealed that seven forearm fractures had previously occurred in five patients and three femoral fractures in two patients. There was a significant reduction in FCAITA (P C 0.05) and Singb grade (P c O.oOl), but not in MCNTA (Table 3). Tlte results of bone histology are shown in Table 4. There was a significant reduc-

Table 4 Bone histomorphometry in 20 men with primary osteoporosis and age-matched control subjects expressed as mean f SE Bone “ohLme

osleaili

WI

faces(%)

IYI.

contrc4 subjects 18.3O~l.M 6.7Oil.08 Primary orteoporakl 1t.* ?, 0.79 8.60 i 1.47 P<0.00, N.S.

Ercdd

IUP

faces(%)

5.9UiOffl 6.80 f 0.73 N.S.

Seam widlh

l-raweldar

nabeeu1ar

@ml)

width Cm)

number (cmJ)

9.38 f 0.40 136.0f 6.0 IO.45 c 0.68 123.5f 5.1 N.S. N.S.

161+ 8 12t+ 10 P < 0.01

353 Table 5

Fasting plasma and urine

biochemistry and radiocalcium absorption (mean + SEM) in men with primary osteoporosis and zge-matched control sutjects (n = number of pairs) Plasmaalkaline phorphatase (K.A. unirs)(n = W) Conlralsubjects 7.57 + 0.45 Primary osleopnroticr 9.63 f 0.57 P < UJJZ

Urine OHPriCr (M) (II = 26)

Urine CalCr (M) Radioealciumabsorption (n = 34) (fractionofdore/h) ,” = 37)

0.012 + 0.001

0.26 * “.W

0.73 f 0.05

0.015 t O.lnn N.S.

O.ZR?;0.03 N.S.

0.51 * 0.04 P
tion in cancellous bone volume which was associated with a non-significant increase in osteoid and eroded surfaces. The seam width was normal and in the nine patients measured the cortical mineral apposition rate (mean + SE) was 0.7 + 0.17ymlday and the cancellous mineral apposition rate (mean + SE) was 0.58 + O.lBpm/day. The trabecular width was normal but trabecular number was significantly decreased (P< 0.01). The results of fasting plasma and urine bioct-mistry and calcium absorption studies are shown in Table 5. The plasma alkaline phosphatase was elevated in the osteoporotic patients (P < 0.02) but urine OHPr/Cr and CaKr were the same in controls and patients. Radiocalcium absorption was significantly lower (P< 0.001) in osteoporotic men than age-matched control subjects. The results of calcium absorption, plasma 2S(OH)D and 1,2S(OH),D in ten men with primary osteoporosis and age-matched normal men are shown in Fig. 2. The lower radiocalcium absorp-

.

:

’

:.

Ftg. 1. Radiocalciumabrorption. plasma 25(OH)D and plarmn I,ZS(OH),D in ten osteoporoticmen

(Of’) and ten age-marchedhealthymen (NORMAL). The meansand Ihe siwificance betweenmeans areshown

354 Table

6

Calciumbalance studies in lb men with primary osteoporosis expressed as mmoU day (mean k SEM) 24.7 * 1.2 21.6 * t.2 5.2 r 0.6 -2.1 f 0.9 3.1 +0.8 6.8 f 0.7 3.5 f 0.6 5.6 r 1.1

Diclnry cakium Faccalcalcium Urine calcium Calciumbalana Net cakium absorption *NC calciumabsorption Mimraliration Rowrptiwl

Table

-_

‘I

Plasma sex steroid concentrations

expressed as mean f SEM in men with primary

osteoporosis and age-matched cot~tml subjects (n = number of pairs) Conirol (nmo!A) (n = 23)

DHEA (nmolll) (ll=ll)

AMkOSteW E, tpmoVl) dione(nmoVl) (n = 21) (II = 22)

Con,ral rubjecs 3S%5+33.2 12.01+2.30 !3.KP+o.99 Primary osteopotks 362.7* 26.6 10.17C 1.37 5.78 + 0.64 N.S. N.S. N.S.

185.8* 15.9 19.4* 1.3

Lo3.0t Lb.,

198.7+ 15.5 19.5f 1.0 N.S. N.S.

86.2 i. 8.9 N.S.

tion was associated with reduced plasma 1,25(OH)1D difference

in the plasma creatinine.

25(OH)D

TestosteroneE, (pm&l) (nmolll) (n=9) (” = 25)

concentrations.

There was no

or PTH concentrations between the

osteoporotic and normal men. Calcium balance in the osteoporotic

men as a group was negative (P < 0.05) be-

cause net calcium absorption was insufficient

to offset urinary calcium loss (Table

6). There were no significant differences in the plasma sex steroid concentrations in the osteoporotic men as compared to controls (Table 7).

This cross-sectional study shows that. in healthy men. cortical and cancellous bone is lost with age and the loss is associated with decreased osteoid surfaces and osteoid seam width. suggesting a reduction in bone formation.

A fall in bone formation with

age is supported by the measurements on trabecular bone architecture which show a reduction with age in trabecular width but not in trabecular number. In contrast. bone resorption

as assessed by eroded surfaces and fasting urine OHPr/Cr

and

355 Ca/Cr. remains constant with age. These age-related changes contrast with those in women, who lose a similar amount of cancellous bone with age but this is associated with a reduction in trabecular number [22] and increased bone resorption [4]. The sex difference in architectural pattern of age-related bone loss probably leads to differences in the structural qualities of bone and may in part contribute to the lower incidence of fractures in men [2,3]. There is also a significant reduction with age in radiocalclum absorption, plasma DHEA and estrone concentrations in healthy men, though the cause of these changes and their relationship to age-related bone loss is unclear from our study. In women we have previously shown that the reduction in calcium absorption with age is due to both declining plasma 25(OH)D concentrations and renal impairment [31], and these may aiso be acting in the case of men [32]. The decrease in plasma DHEA and estronr with age in men is probably the result of a reduced production of adrenal androgens, though if this was the only factor one might also expect a reduction in plasma androstenedionc, which we did not find. Investigation of the osteoporotic men presenting with vertebral crush fractures at a bone clinic shows that about 55% have secondary osteoporosis. Thii is much higher than the 35% we found in women with crush fractures 1331.‘Secondary forms disease causing theosteoporosis should behsp&dly excluded in ihis age group oi patients. Whilst five osteoporotic men admitted to having alcoholism, each of these had another cause of secondary osteoporosis. A high alcohol intake may also have contributed to the development of excess bone loss in some of the men with primary osteoporosis. But alcohol intake is difficult to quantify accurately and the amount which is deleterious to bone is still unknown. Smoking is also reported to be a risk factor for the development of osteoporosis in both men and women [9,15,34], but we have no information on the smoking habits of the men in our study. Nor did we note an association between chronic obstructive airways disease and osteoporosis other than that resulting from steroid therapy, possibly because of the difficulty identifying patients with minor degrees of airways disease and assessing its severity. Like women with crush fracture [2], the men with primary osteoporosis have radiographic evidence of cortical and cancellous bone loss and histological evidence of loss of cancellous bone when compared with control subjects. There is also biochemical evidence of increased bone turnover, although the rises in urinary hydroxyproline and calcium excretion are of a much lower magnitude than those occurring in osteoporotic women and do not reach statistical significance. Nor does the histomorphometry in men show evidence of increased bone resorption although the trabecular architecture does with a lower trabecular number than controls and trabecular width which is normal. Radiocalcium absorption is significantly lower in the ostenporotic men than in age-matched controls and investigation of a subgroup of patients shows that this is associated with reduced plasma 1,25(OH)sD. A recent study of eight men with primary osteoporosis shows a similar reduction in plasma 1,25(OH),D [16]. There is no evidence from our study that thii results from differences in vitamin D status, renal failure or the level of bone resorption as the plasma 25(OH)D, creatinine and PTH are similar in both groups. These results contrast

356 with our findings in osteaporotie women with vertebral crush fractures, where calcium absorption is redurrd compared to age matched control subjects but there is no difference in plasma 1,2.5(OH),D [%I. Nor is it due IO decreased testosterone, which we found is associated with low plazma 1,2S(OH),D concentration in hypogonadal men with osteoporosis 1361.Whatever the cause of the low calcium absotption it is apparently deleterious to the skeleton as, although no calcium balances are available in healthy men. our data show that men with primary osteoporosis are in negative calcium balance.

t RiggsBL. Wuhxr HW. Durm WL, Mares RB, Dfford KP. Melton LJ 111.Differential changesin bone mineral densityof the appcndkularand axial skclem with aging. Rclationsh~p to @“aI o%. leqmrosir. J Cti” lnves~1981:67z328-335. 2 NOrdin BEC. Critty RG, Smith DA. Dsqxwsis. h: Nordin BEC. cd. Ostroparaws.Mctabotk hwe and stow dirrar. 2nd cd”, Edinburgh. Lendon. Metbaume, New York Churchill Livingstone.,Yw,-70. 3 RiggsBL. Uel~o” LJ 111.l”v”luliu”alalcapormir. N En&J Mcd 19&314:1676-1686. 4 Nordin BEC. Aaron J, SpeedR. Crilly RD. Bone f”m&” and rcwrpikm asthe determinantsal trsbcwlsr bonevolumein post~nopausal mteoparosir.Lrmcel198l:ii:277-279. 5 Nordi” BEC. hacock hf. Aaron JE. Crilly RG. HcyburnPJ. Honman A. MarshallD. Oswqxwosis andOneomaltia. Cli” E”d”cnno, Mctab ,980:9:177-205. 6 H~sncy RP. Gallrghrr JC. ,&ns,on CC. Neer R. Parrifirr AM. Whedon GD. Calcium“wiria” and banebe&h in the etderty.Am J Cti” Nuu 1982:36:9+X-1013. 7 Krolner B. Toll B, N&c” SP, TonevoIdE. Phyricalexertire asa prophylaxisagainstinvolutional boneIms. Cli” Sci 1983:u:S4l-$46. 6 At&a J. CohnS, Vwmni AN. Yeh JK. Yhcn K. Ellis K. Risk f~on~orpasuncropsusslarcoporo~1. Am, Mcd 19Rs:78:93-,m.

IU Crilly RG. Marshall DH. Nordin BEC. Effect of age ODplasmaandrostenedione co”Fe”tralio”in ck,phorectomizcd women.Cli” Endoni”“1197~10:199-201. I BullarnorcJR, GallagherJC. WilkinsonR. Nardi” BEC. Manhall DH. Eflect al ageon cakiumabulrplio”. Lance1t97U:ii:S3.5-537. I2 OoltsgherJC. Aaron J. Horrmvn A, Mnrsball DH. Wilkinsa, R. Nordin RFC. The wush frac,u,e syndromein p0stmcnaprvs.lMIIIC”. Clin Ecdocri”otMctsb t973;2:293-315. 13 GallagherJC. RiggsEL, Eisma”1. Hamslra A, Arnaud SE. DeLw HF. lntcstinatcakium absmplion andserumvitaminD mclabolitesin “amal subjectsand .stcopurotic patients.Elfea ofage and calcium. J Cli” lnvesl 1979~64~725-736. I4 Marshall DH. Crilly RG. Nordi” BEC. Plasmaandrorlencdisneand cslro”clevelsin normalsand onecporoticportmcnoprura,wmnc”. Br Med 1 1977:2:,,77-,179. 15 SccmsnE. Melton L1.0.Fa”o” WM. R&s BL. Risk f.xkxs for spinalosteoporosir in men. A”, J Mcd 1983:75:977-983 I6 JackronJA. Kleerckope:M. Parlilt AU. Rao DS. VillanuevaAR. FrameB. Bonehirtomorphometry in hypogonadaland eugonadatme” with qGaI osisopiais. J Cti” Er.tio+nol Melab 198X65:53-58. 17 Savilk PD. The ryndromcol spinalarteopurosir.Cli” EndocrinolMetab t9732: 177-188. 18 Horrmrn A. Nordi” BEC. Simpa” M. SpeedR. Conica, and lrabecutarboneslatusin elderly womenwith Icmoral neckfracture.ClinOrthop 3982:166:143-151 19 SinghM. Naprath AR. Maini PS Changesin trabecularpatlem of the upperend ol the femurasa”

I

dietary

357 index of orteoporosir. J Bone Join, Surg 1970:52A:457-467. 20 Honman

A. Bone mass. In: Nordin

Edinburgh.

London.

New York:

21 Aaron JE. Hirtnlogica, lism. Edinburgh.

methals.

BEC,

ed. Calaum.

Phosphare and magnesium metaboiiw.

Churchill Livingstone. ,9X357-464. In: Nordin BEC. cd. Calcium. phosphate and magncrium metaho-

London. New York: Churchill Livinptone.

19X&h-524.56+568.

22 Aaron JE. Makins NB. Sogreiya K. The microanatomy of trsbecular bone loss in normal aging men andwomen.

ClinOrrhop

23 Aaron JE. Makinr

lY87:215:260-271.

NB. Francis RM.

Peacock M. Slainin

uringcon,na,ingfluorochromcsinvi,ro. 24 Hodgkinurn

of ,he calcificalion fron, in human bone

J His,clCy,ochem

1984;3Z:l251-,261.

A. Thompsoo T. Measurement of ,he fasting urine hydroxyPm,inc:erea~ininc ratio in

normal adds 25 Francis RM.

and itr variarioo with a8c and sex. J Clin Wlha, Pcamek M. Barkwvorlh SA. Marshall DH.

,98*:31:807-811,

A comparison of the effec, of s&i,“,

and

slocose on calcium absormion in oostm~no~aural w.men. Am J Clin Nutr 1986:43:72-76. 26 %ylor

GA. Peacock M, belt 8. &nvn

W:Hohnes

P.. .‘urifica,ion of plusma viramin D mclabolifcs

for radioimmunoassay. Ciin Chim Acta 1980: 108:239-246. 27 MorrisJF,

Peacock M. Arsayofplorma

25-hydroxyvitamin

28 Peacock M, Taylor GA. Brown W. Plasma

D. ClinChim

AFfa 19X%72:383-391.

12S(OH),D measured by radioimmunoaseoy

radioreceptor assay in normal nobjeea and patients wilh primary hyperparalhyroidism oro.C,inChim

29 Peacock M. Rodioimmunoarroy sod magnesium metabelirm. M Nolin

and ey,oso,

and renal iail-

Acm l98v;,U,:93-IUI,

BEC. Cdkium

of pamthyroid hormone. In: Nordin BEC. cd. Calcium. phosphate

Edinburgh.

Laodon. New York: Chorchdl Livingsmns. 1976;556-560.

balallfc and bone ,u,~)yer.

magnesium metabolism. Edinburgh,

In: Nordin BEC. ed. Cakium.

London. New York

phaphalc

and

Churchill Livingstone. 197b:490-498.

3, Francis RM. Peacock M. Barkworth SA. Rena, impairment and in effects on calcium metabolism in elderly women. A8e Agcin8,984:,3:,4-20. 32 Gwol, mfma,

ES, Mcier DE. Alwrationr in cslciom, vitamin D, and parathyroid hormone physiology in men wi,h aging: rekxaoship !o the developmen, of Senile oneopcnir J Clin Endocrinol Me-

lab 19.%;631262-1269. 33 Peacock M. Francis RM. Stomp TCB.

Sclby PL. Vitamin

edr. Oaeqmrosia.

D and oslcoporosir.

A mu,,idiriplinary

In: Dixon ASU. Rwscl,

RGG.

problem. Royal 8ocieIy of Medicine lnternb

liona, Congress and Symporium Seria No. 55. London: Royal Soeioty ofMedicioe/Academic

press.

,983:245-254. 35 De Vemeioul MC. Bielakoff J. Hewe M. Coeds J. Ho,, M, Modrowki D, Konlz D. Mirave, L. Ryckewaert A. Evidmcc for defeaive osteoblastic function. A role for alwlwl and tobacco conrumfxion inosleoporosis in middle-aged men. ClinOnbop

1983:lr):IO7-I

15.

35 Francis RM. Peacwk M, Taylor GA, Storer JH. Nordin BBC. Calrium malabsorption in elderly women wi,h vertebral frac,ores: evidence for resisfance 10 the action of vitamin D metabditer on the blnne,. C,inSci

,98.%66:,03-LO,.

36 Francis RM. Peacock M, Aaron JE. Selby PL, Taylor GA, Thompson 1, Marshall DH, Honman A. On,eoporosis in hypogonadal men: role of decreaxd plasma 1.25.dihydroxyvitamin D. calcium ma,absorption. and low bane formation. Bone 1986:7:261-268.