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Alterations in human serum alkaline phosphatase and its bone isoenzyme by chronic administration of lithium
Clrnrccr Chrnwo Elsevier
151
Ac,ru. 140 (1984) 151-155
CCA 02877
Alterations in human serum alkaline phosphatase and its bone isoenzyme by chronic administration of lithium P.D. Broulik a3*, J.J. !&pBn a, K. SouCek b and V. Pacovsky ” 3rd
Department
of InternalMedtcine
and
Medrcine,
(Received Key words: Lrthium carbonate;
December
h Department
ofPsvchiutyv.
Charles
”
Unioersrt~ Fac~ult~ of
Prague (C:ec~hoslooakia)
15th, 1983: revision March 9th, 1984)
Serum total alkaline phosphatase;
Bone isoeqvme
of serum al,4ulrne
phosphatase
Summary There are conflicting data on the effects of lithium on bone metabolism. Bone formation is known to be reflected by the activity of alkaline phosphatase of the bone tissue. We have found significant differences in mean serum alkaline phosphatase and its bone isoenzyme levels between a group receiving lithium and a control group. In this study increased bone isoenzyme of alkaline phosphatase activity above the normal range was found in 27 of 41 patients treated with lithium carbonate. In 19 of 41 patients treated with lithium the activity of bone isoenzyme was increased above the normal range even in the absence of increased activity of serum total alkaline phosphatase.
Introduction Lithium salts are effective in the treatment of manic-depressive disorders [l]. Lithium administration is associated with a wide variety of mild to toxic side effects [2]. As experience with the drug increases more clinically important side effects become known. There is now evidence that lithium affects calcium metabolism and may sometimes be associated with hyperparathyroidism [3,4]. There are conflicting data on the effects of lithium on bone metabolism. Prolonged administration in rats
* Correspondence should be addressed to Petr D. Broulik MD, 3rd Department of Internal Charles University Faculty of Medicine, U nemocnie 1, Prague 2-12000. Czechoslovakia. CQO9-8981/84/$03.00
0 1984 Elsevier Science Publishers
B.V.
Medicine.
152
resulted in inhibition of bone mineralization and matrix formation with no apparent change in resorption [5]. In another study bone composition was not altered by a similar dose and duration of lithium administration [6]. Bone formation is known to be reflected by the activity of alkaline phosphatase (ALP, EC 3.1.3.1) of the bone tissue [7]. However, the diagnostic value of serum ALP is limited. The bone isoenzyme is thought to be a sensitive and quantitative, though indirect and not absolute, measure of the extent of bone disease [S]. The present study was intended to compare the relationship between total ALP and bone isoenzyme of serum ALP as biochemical indicators of bone formation in patients taking lithium carbonate, and to evaluate the usefulness of this isoenzyme in discriminating between healthy adults and patients treated with lithium with early bone changes. Materials and methods The subjects were 41 psychiatric outpatients of the Psychiatric Hospital, 22 men and 19 women, who ranged in age from 31 to 65 years. All had been diagnosed as having manic-depressive disease and were taking lithium carbonate (10.2220.5 mmol/day in three divided doses with meals) for periods of 20 to 120 months. All patients were under psychiatric observation and their mental illness was well managed by lithium. Patients were without any symptoms of renal, liver or bone disease, with levels of serum creatinine less than 100 pmol/l. Serum lithium was determined by flame spectrophotometry every 3 months [9]. Data concerning sex, age, dose of lithium, duration of treatment and serum lithium levels are presented in Table I. A control group, matched for age and sex, was selected from the original health screening register. No subject in either the observation or the control group used any medical treatment known to affect bone or calcium metabolism. The total activity of serum ALP and its bone, liver and intestinal isoenzymes were determined with 4-nitrophenylphosphate as substrate using a modified inactivationinhibition method [lo], with a normal range for ALP 0.100-0.666 pkat/l, and for B-ALP 0.090-0.266 pkat/l. The total concentration of calcium in the serum was determined by a complexometric method [ll]. Inorganic phosphate was determined photometrically [12]. The results were evaluated by using standard parametric statistical techniques 1131.
TABLE
I
Sex, age and load of lithium Lithium patients No. 41
treated
in 41 lithium
treated
patients
Sex
Duration of treatment (months) mean + SD
Dose of lithium (mmol/day) mean * SD
Serum lithium (mmol/l) mean + SD
Age mean + SD
19 F
65.3 + 39.7
12.30 k 2.65
0.48+0.12
44.1* 9.4
22 M
53.4 + 34.2
13.97 k 3.42
0.58iO.16
45.9 & 9.3
153
Results
There were significant differences in mean serum ALP and its bone isoenzyme levels between the group with lithium and the control group ( p -c0.001,Table II). However, the diagnostic significance of the total activity of serum ALP in patients treated with lithium carbonate was not adequate. In 80.5% of the patients treated with lithium ALP was within normal limits. In 19.5% of the tested patients ALP was increased above normal limits. The increase was always due to increased bone isoenzyme activity. Determination of the total activity of ALP in patients treated with lithium was of diagnostic help only in 8 of 41 patients. However, markedly increased activity of bone isoenzyme of serum ALP above the normal range was found in 65.8% of the patients on lithium treatment (Fig. 1). In 19 of the 41 patients treated with lithium the activity of bone isoenzyme was increased above the normal range even in the absence of increased activity of total ALP. We did not find any positive correlations between duration of treatment and increase in bone isoenzyme activity.
. .
: . 0.4
.
female
.
male
l: l
p
0.3
0.2
0.1
Z Fig. 1. Activity of bone isoenzyme of serum alkaline phosphatases in lithium treated patients control group. Each symbol represents 1 patient. Shaded area indicates the normal range.
and a
154
TABLE
II
Biochemical
values in lithium treated patients and in healthy adults Lithium treated
Control group
n = 41
n = 20
mean + SD
mean k SD
ALP (pkat,‘l)
0.542*0.15
*
0.386+0.10
B-ALP
0.301 kO.10
*
0.149~0.05
(pkat/l)
1.02OkO.17
1.030+0.10
Calcium (mmol/l)
2.500t0.15
2.530*0.15
Potassium (mmol/l)
4.360 +0.30
4.380 * 0.34
Inorganic
phosphate (mmol/l)
*p < 0.001.
Serum calcium was within the normal range (2.1-2.85 mmol/l) in the group of lithium treated patients. Serum phosphorus also was within the normal range (0.80-1.45 mmol/l) in this group. There were no significant differences in mean serum calcium levels between the group taking lithium and the control group. Discussion The specificity and sensitivity of the measurement of total ALP activity is substantially increased by an evaluation of its isoenzymes. The activity of B-ALP in serum is proportional to the bone cellular activity, to the amount of osteoid seams and to the extent of remodelling of bone [8]. In spite of highly significant differences in mean serum ALP and its bone isoenzyme levels between the group taking lithium and the control group we have tried to analyse the group of patients treated with lithium. In this study increased B-ALP activity above the normal range was found in 27 of 41 patients treated with lithium carbonate. It seems therefore that it is predominantly the extracellular alkaline phosphatase of the bone matrix which passes into serum. This enzyme is then of diagnostic value, provided that it is distinguished from the other organ-specific alkaline phosphatases in serum [14]. Even slightly increased skeletal remodelling can be detected in patients treated with lithium. Analysis of isoenzymes which participate in the total alkaline phosphatase activity in serum allows determination of an abnormal increase in the activity of bone-specific isoenzyme. This is true even in the absence of an enhanced total alkaline phosphatase activity which is found in patients treated with lithium. In this study the action of lithium on bone was demonstrable in only 19.5% of the patients by increased total activity of serum ALP above the normal range, whereas the bone isoenzyme activity was increased above the normal range in 65.8% of the patients. No rise of the serum calcium and phosphorus levels was found in our patients treated with lithium carbonate. The results show that prolonged treatment with lithium is not followed by convincing changes in serum calcium and phosphorus. The mechanism behind the apparent association between lithium therapy and
155
bone involvement calls for further investigation. Since lithium is used over long periods in the prophylactic treatment of periodic affective disorders, it is important to determine whether or not it has long-term deleterious effects on bone. We suggest that the total ALP and bone isoenzyme of ALP should be checked routinely in patients on lithium. There are a number of possible mechanisms by which lithium elevates bone isoenzyme of ALP [2,15-171. To investigate these mechanisms was beyond purpose of this paper. References 1 Schon M. Lithium in psychiatric therapy and prophylaxis. J Psychiat Rev 1968: 6: 67770. 2 Davis BM, Pfefferbaum A. Krutzik S. Davis KL. Lithium’s effect on parathyroid hormone. Am J Psychiat 1981; 138: 489-493. 3 Christiansen C, Baastrup PC, Lindgreen P. Transbol I. Endocrine effects of lithium, primary hyperparathyroidism. Acta Endocrinol 1978; 88: 528-534. 4 Birch NJ, Jenner FA. The distribution of lithium and its effects on the distribution and excretion of other ions in the rat. J Pharmacol 1973; 47: 586-590. 5 Baran DT, Schwartz MP, Bergfeld MA, Teitelbaum SL, Slatopolsky LV, Avioli LV. Lithium inhibition of bone mineralization and osteoid formation. J Clin Invest 1978; 61: 1691-1694. 6 Henneman D, Zimmerberg JJ. Lack of effect of chronic lithium chloride on bone composition and metabolism. Endocrinology 1974; 94: 915-919. 7 Lauffenburger T. Olah AJ, Dambacker MA. Cuncaga J, Lentner CH, Haas HG. Bone remodeling and calcium metabolism: a correlated histomorphometric. calcium kinetic and biochemical study in patients with osteoporosis and Paget’s disease. Metabolism 1977; 26: 589-606. 8 Stepan J, Pacovsky V. Horn V et al. Relationship of the activity of the bone isoenzyme of serum alkaline phosphatase to urinary hydroxyproline excretion in metabolic and neoplastic bone diseases. Em J Clin Invest 1978; 8: 373-377. 9 Amdisen A. Serum lithium determination for clinical use. J Clin Lab Invest 1967; 20: 104-108. 10 Stepan J, Volek V, Kolai J. A modified inactivation-inhibition method for determining the serum activity of alkaline phosphatase isoenzymes. Clin Chim Acta 1976; 69: l-9. 11 Gitelman HJ. An improved automated procedure for the determination of calcium in biological specimens. Anal Biochem 1967; 18: 521-531. 12 Kraml M. A semiautomated determination of phospholipids. Clin Chim Acta 1966; 13: 442-448. 13 Finney DJ. Statistical method in biological assay, 2nd ed. London: Griffin, 1967. 14 Stepan J, Marek J, Havranek T. Doleial V, Pacovsky V. Bone isoenzyme of serum alkaline phosphatase in acromegaly. Clin Chim Acta 1979; 93: 355-363. 15 Herman SP. Lithium, hypercalcemia and hyperparathyroidism. Biol Psychiat 1981; 16: 593-595. 16 Christensson TAT. Lithium, hypercalcemia and hyperparathyroidism. Lancet 1976; i: 144. 17 Christiansen C, Baastrup PC. Lithium induced ‘primary hyperparathyroidism’. Calcif Tiss Res 1977; suppl. 22: 341-343.
151
Ac,ru. 140 (1984) 151-155
CCA 02877
Alterations in human serum alkaline phosphatase and its bone isoenzyme by chronic administration of lithium P.D. Broulik a3*, J.J. !&pBn a, K. SouCek b and V. Pacovsky ” 3rd
Department
of InternalMedtcine
and
Medrcine,
(Received Key words: Lrthium carbonate;
December
h Department
ofPsvchiutyv.
Charles
”
Unioersrt~ Fac~ult~ of
Prague (C:ec~hoslooakia)
15th, 1983: revision March 9th, 1984)
Serum total alkaline phosphatase;
Bone isoeqvme
of serum al,4ulrne
phosphatase
Summary There are conflicting data on the effects of lithium on bone metabolism. Bone formation is known to be reflected by the activity of alkaline phosphatase of the bone tissue. We have found significant differences in mean serum alkaline phosphatase and its bone isoenzyme levels between a group receiving lithium and a control group. In this study increased bone isoenzyme of alkaline phosphatase activity above the normal range was found in 27 of 41 patients treated with lithium carbonate. In 19 of 41 patients treated with lithium the activity of bone isoenzyme was increased above the normal range even in the absence of increased activity of serum total alkaline phosphatase.
Introduction Lithium salts are effective in the treatment of manic-depressive disorders [l]. Lithium administration is associated with a wide variety of mild to toxic side effects [2]. As experience with the drug increases more clinically important side effects become known. There is now evidence that lithium affects calcium metabolism and may sometimes be associated with hyperparathyroidism [3,4]. There are conflicting data on the effects of lithium on bone metabolism. Prolonged administration in rats
* Correspondence should be addressed to Petr D. Broulik MD, 3rd Department of Internal Charles University Faculty of Medicine, U nemocnie 1, Prague 2-12000. Czechoslovakia. CQO9-8981/84/$03.00
0 1984 Elsevier Science Publishers
B.V.
Medicine.
152
resulted in inhibition of bone mineralization and matrix formation with no apparent change in resorption [5]. In another study bone composition was not altered by a similar dose and duration of lithium administration [6]. Bone formation is known to be reflected by the activity of alkaline phosphatase (ALP, EC 3.1.3.1) of the bone tissue [7]. However, the diagnostic value of serum ALP is limited. The bone isoenzyme is thought to be a sensitive and quantitative, though indirect and not absolute, measure of the extent of bone disease [S]. The present study was intended to compare the relationship between total ALP and bone isoenzyme of serum ALP as biochemical indicators of bone formation in patients taking lithium carbonate, and to evaluate the usefulness of this isoenzyme in discriminating between healthy adults and patients treated with lithium with early bone changes. Materials and methods The subjects were 41 psychiatric outpatients of the Psychiatric Hospital, 22 men and 19 women, who ranged in age from 31 to 65 years. All had been diagnosed as having manic-depressive disease and were taking lithium carbonate (10.2220.5 mmol/day in three divided doses with meals) for periods of 20 to 120 months. All patients were under psychiatric observation and their mental illness was well managed by lithium. Patients were without any symptoms of renal, liver or bone disease, with levels of serum creatinine less than 100 pmol/l. Serum lithium was determined by flame spectrophotometry every 3 months [9]. Data concerning sex, age, dose of lithium, duration of treatment and serum lithium levels are presented in Table I. A control group, matched for age and sex, was selected from the original health screening register. No subject in either the observation or the control group used any medical treatment known to affect bone or calcium metabolism. The total activity of serum ALP and its bone, liver and intestinal isoenzymes were determined with 4-nitrophenylphosphate as substrate using a modified inactivationinhibition method [lo], with a normal range for ALP 0.100-0.666 pkat/l, and for B-ALP 0.090-0.266 pkat/l. The total concentration of calcium in the serum was determined by a complexometric method [ll]. Inorganic phosphate was determined photometrically [12]. The results were evaluated by using standard parametric statistical techniques 1131.
TABLE
I
Sex, age and load of lithium Lithium patients No. 41
treated
in 41 lithium
treated
patients
Sex
Duration of treatment (months) mean + SD
Dose of lithium (mmol/day) mean * SD
Serum lithium (mmol/l) mean + SD
Age mean + SD
19 F
65.3 + 39.7
12.30 k 2.65
0.48+0.12
44.1* 9.4
22 M
53.4 + 34.2
13.97 k 3.42
0.58iO.16
45.9 & 9.3
153
Results
There were significant differences in mean serum ALP and its bone isoenzyme levels between the group with lithium and the control group ( p -c0.001,Table II). However, the diagnostic significance of the total activity of serum ALP in patients treated with lithium carbonate was not adequate. In 80.5% of the patients treated with lithium ALP was within normal limits. In 19.5% of the tested patients ALP was increased above normal limits. The increase was always due to increased bone isoenzyme activity. Determination of the total activity of ALP in patients treated with lithium was of diagnostic help only in 8 of 41 patients. However, markedly increased activity of bone isoenzyme of serum ALP above the normal range was found in 65.8% of the patients on lithium treatment (Fig. 1). In 19 of the 41 patients treated with lithium the activity of bone isoenzyme was increased above the normal range even in the absence of increased activity of total ALP. We did not find any positive correlations between duration of treatment and increase in bone isoenzyme activity.
. .
: . 0.4
.
female
.
male
l: l
p
0.3
0.2
0.1
Z Fig. 1. Activity of bone isoenzyme of serum alkaline phosphatases in lithium treated patients control group. Each symbol represents 1 patient. Shaded area indicates the normal range.
and a
154
TABLE
II
Biochemical
values in lithium treated patients and in healthy adults Lithium treated
Control group
n = 41
n = 20
mean + SD
mean k SD
ALP (pkat,‘l)
0.542*0.15
*
0.386+0.10
B-ALP
0.301 kO.10
*
0.149~0.05
(pkat/l)
1.02OkO.17
1.030+0.10
Calcium (mmol/l)
2.500t0.15
2.530*0.15
Potassium (mmol/l)
4.360 +0.30
4.380 * 0.34
Inorganic
phosphate (mmol/l)
*p < 0.001.
Serum calcium was within the normal range (2.1-2.85 mmol/l) in the group of lithium treated patients. Serum phosphorus also was within the normal range (0.80-1.45 mmol/l) in this group. There were no significant differences in mean serum calcium levels between the group taking lithium and the control group. Discussion The specificity and sensitivity of the measurement of total ALP activity is substantially increased by an evaluation of its isoenzymes. The activity of B-ALP in serum is proportional to the bone cellular activity, to the amount of osteoid seams and to the extent of remodelling of bone [8]. In spite of highly significant differences in mean serum ALP and its bone isoenzyme levels between the group taking lithium and the control group we have tried to analyse the group of patients treated with lithium. In this study increased B-ALP activity above the normal range was found in 27 of 41 patients treated with lithium carbonate. It seems therefore that it is predominantly the extracellular alkaline phosphatase of the bone matrix which passes into serum. This enzyme is then of diagnostic value, provided that it is distinguished from the other organ-specific alkaline phosphatases in serum [14]. Even slightly increased skeletal remodelling can be detected in patients treated with lithium. Analysis of isoenzymes which participate in the total alkaline phosphatase activity in serum allows determination of an abnormal increase in the activity of bone-specific isoenzyme. This is true even in the absence of an enhanced total alkaline phosphatase activity which is found in patients treated with lithium. In this study the action of lithium on bone was demonstrable in only 19.5% of the patients by increased total activity of serum ALP above the normal range, whereas the bone isoenzyme activity was increased above the normal range in 65.8% of the patients. No rise of the serum calcium and phosphorus levels was found in our patients treated with lithium carbonate. The results show that prolonged treatment with lithium is not followed by convincing changes in serum calcium and phosphorus. The mechanism behind the apparent association between lithium therapy and
155
bone involvement calls for further investigation. Since lithium is used over long periods in the prophylactic treatment of periodic affective disorders, it is important to determine whether or not it has long-term deleterious effects on bone. We suggest that the total ALP and bone isoenzyme of ALP should be checked routinely in patients on lithium. There are a number of possible mechanisms by which lithium elevates bone isoenzyme of ALP [2,15-171. To investigate these mechanisms was beyond purpose of this paper. References 1 Schon M. Lithium in psychiatric therapy and prophylaxis. J Psychiat Rev 1968: 6: 67770. 2 Davis BM, Pfefferbaum A. Krutzik S. Davis KL. Lithium’s effect on parathyroid hormone. Am J Psychiat 1981; 138: 489-493. 3 Christiansen C, Baastrup PC, Lindgreen P. Transbol I. Endocrine effects of lithium, primary hyperparathyroidism. Acta Endocrinol 1978; 88: 528-534. 4 Birch NJ, Jenner FA. The distribution of lithium and its effects on the distribution and excretion of other ions in the rat. J Pharmacol 1973; 47: 586-590. 5 Baran DT, Schwartz MP, Bergfeld MA, Teitelbaum SL, Slatopolsky LV, Avioli LV. Lithium inhibition of bone mineralization and osteoid formation. J Clin Invest 1978; 61: 1691-1694. 6 Henneman D, Zimmerberg JJ. Lack of effect of chronic lithium chloride on bone composition and metabolism. Endocrinology 1974; 94: 915-919. 7 Lauffenburger T. Olah AJ, Dambacker MA. Cuncaga J, Lentner CH, Haas HG. Bone remodeling and calcium metabolism: a correlated histomorphometric. calcium kinetic and biochemical study in patients with osteoporosis and Paget’s disease. Metabolism 1977; 26: 589-606. 8 Stepan J, Pacovsky V. Horn V et al. Relationship of the activity of the bone isoenzyme of serum alkaline phosphatase to urinary hydroxyproline excretion in metabolic and neoplastic bone diseases. Em J Clin Invest 1978; 8: 373-377. 9 Amdisen A. Serum lithium determination for clinical use. J Clin Lab Invest 1967; 20: 104-108. 10 Stepan J, Volek V, Kolai J. A modified inactivation-inhibition method for determining the serum activity of alkaline phosphatase isoenzymes. Clin Chim Acta 1976; 69: l-9. 11 Gitelman HJ. An improved automated procedure for the determination of calcium in biological specimens. Anal Biochem 1967; 18: 521-531. 12 Kraml M. A semiautomated determination of phospholipids. Clin Chim Acta 1966; 13: 442-448. 13 Finney DJ. Statistical method in biological assay, 2nd ed. London: Griffin, 1967. 14 Stepan J, Marek J, Havranek T. Doleial V, Pacovsky V. Bone isoenzyme of serum alkaline phosphatase in acromegaly. Clin Chim Acta 1979; 93: 355-363. 15 Herman SP. Lithium, hypercalcemia and hyperparathyroidism. Biol Psychiat 1981; 16: 593-595. 16 Christensson TAT. Lithium, hypercalcemia and hyperparathyroidism. Lancet 1976; i: 144. 17 Christiansen C, Baastrup PC. Lithium induced ‘primary hyperparathyroidism’. Calcif Tiss Res 1977; suppl. 22: 341-343.