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J Bone Miner Metab (2002) 20:39–43
© Springer-Verlag 2002
The role of trace minerals in the pathogenesis of postmenopausal
osteoporosis and a new effect of calcitonin
Ali Gür
1
, Leyla Çolpan
2
, Kemal Nas
1
, Remzi Çevik
1
, Jale Saraç
1
, Ferda Erdog˘an
1
, and M. Zahir Düz
3
1
Physical Medicine and Rehabilitation, Dicle University School of Medicine, Diyarbakır, Turkey
2
Department of Biochemistry, Dicle University School of Medicine, Diyarbakır, Turkey
3
Department of Chemistry, Faculty of Science and Art, Dicle University, Diyarbakır, Turkey
Introduction
Osteoporosis is a condition of bone fragility resulting
from microarchitectural deterioration and decreased
bone mass. Adult bone mass depends on the peak at-
tained and the rate of subsequent loss. Each component
depends on the interaction of genetic, hormonal, envi-
ronmental, and nutritional factors [1]. Trace minerals
may be important in maintaining bone quality through
their role as metalloenzymes in the synthesis of collagen
and other proteins that form the structure of bone
[2].
The risk of nutritional disturbances, in particular,
trace element and vitamin deficiencies, is high during
menopause. The participation of trace minerals in nor-
mal development and maintenance of the skeleton is
related to their catalytic functions in organic bone ma-
trix synthesis [3,4]. Trace elements are essential for nor-
mal growth and development of the skeleton in humans
and animals. Although they are minor building compo-
nents in teeth and bone, they play important functional
roles in bone metabolism and bone turnover. Magne-
sium (Mg) enhances bone turnover through the stimula-
tion of osteoclastic function. It has been suggested that
Mg deficiency may play a role in postmenopausal os-
teoporosis [5]. Zinc [Zn] regulates secretion of calcito-
nin from the thyroid gland and has an influence on bone
turnover [6]. Copper (Cu) induces low bone turnover by
suppression of both osteoblastic and osteoclastic func-
tions [5].
The significance of Mg in bone metabolism and in the
development of metabolic bone disease has not been
sufficiently elucidated. Mg acts as a surrogate for cal-
cium (Ca) in transport and mineralization processes
[7,8], but it also exerts a large number of other actions,
including enzyme cofactor function and modulation of
the action of hormones, growth factors, and cytokines.
Mg also has direct effects on the bone formation pro-
cesses of resorption and mineral aggregation [9].
Abstract The physiologic role of calcitonin in mineral and
bone homeostasis is not very well understood. Very few longi-
tudinal studies have reported the effects of calcitonin therapy
on trace minerals in postmenopausal osteoporosis despite the
documented involvement of trace minerals in normal skeletal
metabolism. Several trace minerals, particularly magnesium
(Mg) and zinc (Zn), essential for organic bone matrix synthe-
sis have been known for at least three decades. The present
study was designed to determine whether the mineral profile
was different between 70 osteoporotic and 30 nonosteoporotic
postmenopausal women and to evaluate the efficacy of calci-
tonin therapy for 6 months on these trace minerals in post-
menopausal osteoporotic women. In our study, the serum
values of Mg, copper (Cu), and Zn (P ⬍ 0.05) were
significantly lower in the patient group than those in the con-
trol group. After 3 months of treatment, serum Cu, Zn, and
Mg levels did not differ between the patients and controls, and
this situation has continued after the end of 6 months of
therapy. Serum Cu, Zn, and Mg levels increased consistently
during the 6-month treatment period. The higher levels of
serum Mg in the 3rd and 6th months of therapy were found to
be statistically significant compared to those before treatment
(P ⬍ 0.05). Serum Cu and Zn levels were found to be
significantly higher at all measurements during the treatment
period as well as at the end of therapy (P ⬍ 0.05). These
results suggest that (1) calcitonin therapy regulates Mg, Cu,
and Zn levels in postmenopausal osteoporosis; (2) when se-
rum calcium and phosphorus were normal in postmenopausal
osteoporosis, serum Mg, Cu, and Zn were more useful for
evaluation; and (3) further studies are essential to evaluate
the role of dietary composition on the manifestations of
osteoporosis.
Key words calcitonin therapy · copper · magnesium · post-
menopausal osteoporosis · zinc
Offprint requests to: A. Gür
Received: March 28, 2001 / Accepted: July 2, 2001
40 A. Gür et al.: Trace minerals in postmenopausal osteoporosis and calcitonin
The adverse effect of trace mineral deprivation on
bone metabolism in animals has been recognized for
many years and is known to be related to specific defects
in organic bone matrix synthesis. Zn deficiency causes
a reduction in osteoblastic activity, collagen and chon-
droitin sulfate synthesis, and alkaline phosphatase
(ALP) activity [10,11]. Cu, a cofactor for lysyl oxidase,
is required in the cross-linking of collagen and elastin
[12,13]. Zinc is essential for life and reproduction and is
a component of the cell nucleus, mitochondria, cyto-
plasm, cell membranes, and cell walls [14]. Zinc is a
constituent of about 300 enzymes, and Zn ions are
located in the catalytic site as well as in the structural
site of the enzyme complex [15,16]. ALP, an enzyme
involved in bone metabolism, is in the family of Zn
enzymes. Among the trace elements in bone and hair,
significant differences were found between normal sub-
jects and osteoporotic patients in Zn, Cu, and manga-
nese (Mn) content. However, the exact involvement of
the trace elements in osteoporosis has not yet been
clarified [5].
The biological effects of calcitonin may be divided
into those related to Ca and P homeostasis and those
related to gastrointestinal function [6]. The administra-
tion of calcitonin decreases renal tubular resorption
of Ca and P as well as that of sodium (Na), potas-
sium (K), and Mg [17]. To our knowledge, despite the
documented involvement of trace minerals in normal
skeletal metabolism, there have been no previous
longitudinal studies reporting the effects of calcitonin
therapy on trace minerals in postmenopausal os-
teoporosis. Thus, this longitudinal study may present a
new concept: that calcitonin treatment improves os-
teoporosis by modulating trace minerals as well as by
the reduction of osteoclastic bone resorption.
The present study was designed to determine
whether the mineral profile differed between osteo-
porotic and nonosteoporotic postmenopausal women
and to evaluate the efficacy of calcitonin therapy during
6 months on these trace minerals in postmenopausal
osteoporotic women.
Patients and methods
All 75 patients in the study were postmenopausal os-
teoporotic women and were selected from the Depart-
ment of Physical Therapy and Rehabilitation of Dicle
University Hospital. Their ages varied from 54 to 73
years for the patients with postmenopausal osteoporosis
and from 50 to 68 years for the controls (the mean ages
of the groups were not significantly different). Women
were eligible for our study if they were 50 years of
age or older and in good general health as determined
by medical history and routine clinical blood analysis
(complete blood counts and differential count). Women
were excluded if they (1) had used any drug or had any
disease or condition known to affect bone or calcium
metabolism; (2) had taken corticosteroid medications
during the previous 6 months; (3) had a history of
chronic renal, hepatic, or gastrointestinal disease or
lumbar compression fracture; or (4) had evidence of
collapsed or focal vertebral sclerosis. Based on these
criteria, 75 postmenopausal osteoporotic and 30 post-
menopausal nonosteoporotic women were included in
the study. All procedures were approved by the Human
Studies Research Committee of the University of Dicle,
Diyarbakir, Turkey, and written informed consent was
obtained from each patient and control before inclusion
in the study. Two women left the study after base-
line measurements, and 3 patients stopped calcitonin
therapy and were excluded, resulting in 70 osteoporotic
women for analysis. The medications administered
were calcitonin (100IU i.m./daily for the first week,
every other day for the second week, and three times
weekly for the third week and there after) with daily
1000 mg calcium supplements. Medications were not
administered in the control group.
We measured bone mineral density (BMD) with
posteroanterior projection, using standard techniques
from dual-energy X-ray absorptiometry (Hologic QDR
model 1000; Hologic, Waltham, MA, USA). The varia-
tion coefficient for consecutive determinations on spine
and femur images in our laboratory was 1.8% at the
lumbar spine and 1.5% at the femur region. All spinal
scans were reviewed for evidence of vertebrae with col-
lapse or focal sclerosis by an experienced radiologist.
Blood was obtained after overnight fasting, and pre-
cautions were taken to avoid contamination. Blood
samples were collected in trace element-free vacutainer
tubes. Serum was separated using acid-washed pipettes,
diluted with distilled water, and stored in acid-cleaned
microcentrifuge tubes at 4°C. Serum Cu, Mg, and Zn
concentrations were determined using atomic absorp-
tion spectrophotometry (GE496623 UNICAM 929,
England). Serum chemical estimations were performed
using Beckman-Synchron CX-5 technology, USA. Zinc,
Cu, Mg, Ca, phosphate, and ALP levels were measured
in blood before calcitonin therapy and again after 1
week and 1, 3, and 6 months in postmenopausal oste-
oporotic women and at baseline in the control group.
Statistical analysis was carried out using the
STATISTICA program for Windows. A median and
standard deviation were calculated for each variable
measured. Data were analyzed for significance using
the unpaired two-tailed t test. The effect of calcitonin
therapy on the biochemical markers during the 6
months of treatment (after 1 week and after 1, 3, and 6
months) was evaluated by the paired t test comparing
each time period with baseline (before treatment). The
A. Gür et al.: Trace minerals in postmenopausal osteoporosis and calcitonin 41
measurements at different time points were considered
independent comparisons between groups because
there were sequential. One-way analysis of variance
(ANOVA) was applied as the statistical test. If any
significance was found, a post hoc test was used. P
values ⬍0.05 were accepted as statistically significant.
Results
Seventy osteoporotic women aged 60.835 ⫾ 4.896 (52–
73) years and 30 nonosteoporotic women aged 61.123 ⫾
5.28 (50–70) years took part in the study. A profile of
several characteristics of the 70 osteoporotic women
and 30 healthy controls, who completed the study is
presented in Table 1. At baseline, osteoporotic and
nonosteoporotic women did not differ in age, serum Ca,
ALP, and P (P ⬎ 0.05).
In our study, the serum values of Mg (P ⬍ 0.05), Cu
(P ⬍ 0.05), and Zn (P ⬍ 0.05) before treatment were
significantly lower in the before treatment patient group
than in the control group (Table 1). After the end of 3
months of treatment, serum Cu, Zn, and Mg levels were
not different between the patient and controls, and this
situation has continued past the end of 6 months of
therapy (Table 2).
Serum Cu, Zn, and Mg levels increased steadily dur-
ing the 6 months of treatment. The levels of serum Mg in
the 3rd and 6th months of therapy were found to be
significantly higher than those before treatment (P ⬍
0.05). Serum Cu and Zn levels were found to be
significantly higher in all measurements during the treat-
ment period as well as at the end of the therapy com-
pared to those before treatment (P ⬍ 0.05) (Table 2).
Discussion
The adverse effect of trace mineral deprivation on bone
metabolism in animals has been recognized for many
years and is known to be related to specific defects in
organic bone matrix synthesis. Zn deficiency causes a
reduction in osteoblastic activity, collagen and chon-
droitin sulfate synthesis, and ALP activity [5]. Cu, a
cofactor for lysyl oxidase, is required in the cross-
linking of collagen and elastin [3,18].
Tranquilli et al. [19] have reported that the uptake of
Ca, P, and Mg is low in women with postmenopausal
Table 1. Profile of several characteristics of the 70 postmenopausal osteoporotic
women and 30 controls who completed the study
Variable Patient group (n ⫽ 70) Control group (n ⫽ 30)
Age (years) 60.83 ⫾ 4.89
NS
61.12 ⫾ 5.28
Serum Mg (ppm) 26.99 ⫾ 7.38* 32.52 ⫾ 6.23
Serum Cu (ppm) 1.59 ⫾ 0.64* 2.09 ⫾ 0.75
Serum Zn (ppm) 0.61 ⫾ 0.425* 1.22 ⫾ 0.31
Serum Ca (mg/dl) 9.36 ⫾ 0.83
NS
9.61 ⫾ 0.47
Serum ALP (IU/l) 83.25 ⫾ 22.63
NS
82.62 ⫾ 22.48
Serum P (mg/dl) 3.57 ⫾ 0.653
NS
3.65 ⫾ 0.478
BMD
L2–4 (g/cm
2
) 0.69 ⫾ 0.35* 1.45 ⫾ 0.58
L2–4 (Z score) ⫺2.96 ⫾ 1.09* ⫺0.89 ⫾ 0.68
Femoral neck (g/cm
2
) 0.70 ⫾ 0.12* 1.08 ⫾ 0.41
Femoral neck (Z score) ⫺2.65 ⫾ 1.07* ⫺0.92 ⫾ 0.39
Values are shown as mean ⫾ standard deviation (SD) for all variables;
ALP, alkaline phosphatase; BMD, bone mineral density; NS, not significant
* Significantly different from control group (P ⬍ 0.05)
Table 2. Comparisons of serum magnesium (Mg), cooper (Cu), and Zinc (Zn) levels in controls and patients receiving calcitonin
treatment for 6 months
Variable (ppm) Control Before treatment 1st week 1st month 3rd month 6th month
Serum Mg 32.52 ⫾ 6.23 26.989 ⫾ 7.38* 27.372 ⫾ 6.98* 28.963 ⫾ 6.27* 31.05 ⫾ 4.29** 32.072 ⫾ 2.98**
Serum Cu 2.09 ⫾ 0.75 1.592 ⫾ 0.64* 1.609 ⫾ 0.59*
,
** 1.649 ⫾ 0.61*
,
** 1.796 ⫾ 0.33** 1.976 ⫾ 0.27**
Serum Zn 1.22 ⫾ 0.31 0.609 ⫾ 0.37* 0.646 ⫾ 0.34*
,
** 0.765 ⫾ 0.36*
,
** 0.927 ⫾ 0.40** 1.082 ⫾ 0.32**
Values are mean ⫾ standard deviation for all variables; values not sharing a common superscript are significantly different
* Significantly different from values in control group (P ⬍ 0.05)
** Significantly different from values before treatment in patients (P ⬍ 0.05)
42 A. Gür et al.: Trace minerals in postmenopausal osteoporosis and calcitonin
osteoporosis as compared to the control group and that
this correlated with bone mineral content (BMC). Car-
penter and colleagues [20] have demonstrated that Mg
deficiency had an effect on osteocalcin synthesis and
secretion and that this resulted in decreased osteocalcin
synthesis. Wallach [9] and Cohen [21] found serum Mg
in osteoporotic women was significantly lower than the
value in matched normal subjects. Conversely, Steidl et
al. [22] found a significant decrease in erythrocyte Mg
content in patients with postmenopausal and senile
osteoporosis but not in their serum levels.
Elevated serum Cu may in itself be a mechanism by
which the Cu supply to bony tissue is increased and
maintenance of the organic matrix is enhanced. The
roles of several trace minerals in bone metabolism, in
particular Cu, have been extensively studied in experi-
mental animals [3]. The oxidative deamination of lysyl
or hydroxilysyl residues by the Cu-dependent enzyme
lysyl oxidase is believed to be the sole initiator of cross-
link formation [23]. Thus, Cu is required throughout life
for the completion of the bone remodeling cycle.
Bunchman [24] and Yee et al. [25] have reported that
Cu deficiency resulted in postmenopausal osteoporosis.
Cross-sectional studies demonstrated a strong correla-
tion between low BMD, low dietary Ca intake, and
serum Cu levels in postmenopausal women [3]. Many in
vitro and in vivo studies of ovariectomized animals have
reported that Zn has an anabolic effect on bone me-
tabolism by inhibiting bone resorption and stimulating
bone formation [26–28].
Because several reports have suggested the role of Zn
ion in bone metabolism, we decided to examine the
levels of Zn in patients with osteoporosis. However, the
role of Zn deficiency in osteoporosis is unclear. Zn also
helps to stabilize the cell membrane structure and thus
has an inhibitory effect on the disruption of mast cells.
Zn depletion therefore leads to degranulation of mast
cells and release of endogenous heparin-containing
granules. Endogenous heparin may contribute to the
pathogenesis of osteoporosis, and, on the basis of avail-
able experimental and clinical evidence, Zn depletion
may also have a role [10]. Relea et al. [29] have reported
that the urinary clearance of Zn in postmenopausal
women was higher than in premenopausal women.
Steidl et al. [30] found that serum Zn levels were lower
among patients with postmenopausal osteoporosis than
in controls.
In our study, Mg, Zn, and Cu levels in the serum of
patients with postmenopausal osteoporosis were lower
than those in the control group. Our findings indicate
that further investigations must be made to evaluate the
role of Mg, Zn, and Cu deficiency in metabolic bone
disease. Although calcitonin is viewed as a major cal-
cium-regulating factor because of its calcium-lowering
and phosphorus-lowering tendency, its precise physi-
ologic role is unknown [8]. Further work is necessary to
confirm these preliminary findings and to delineate
clearly the mechanisms of action in animal studies.
The most notable finding in our study was the in-
creased serum Cu, Mg, and Zn levels during the therapy
period in patients who received calcitonin therapy. In
this study, it was demonstrated that the administration
of calcitonin and Ca can be a fast, effective treatment.
Several mechanisms may be involved in the effect of
calcitonin. One of these mechanisms is that the blood
levels of Zn and Mg, which are needed for the growth
and density of bone, are increased by calcitonin via
induction of the renal tubular reabsorption of these
elements. Furthermore, calcitonin protects against de-
creased BMD by lowering the bone resorption rate.
As demonstrated by previous studies, the deficiency
of trace elements plays a major role in the develop-
ment of osteoporosis [9,21,22,24,25,30]. However, the
effect of calcitonin on these elements is not very well
known. Elucidation of the metabolic mechanisms of the
enhancing effect of calcitonin on serum Cu, Zn, and Mg
levels requires further studies. We think that further
insights into the mechanisms involved in the increasing
effect of calcitonin on trace element levels will help us
to understand osteoporosis better.
In summary, these results suggest that (1) calcitonin
treatment has a modulatory role on serum Mg, Cu, and
Zn levels in postmenopausal osteoporotic women; (2)
when serum Ca and P were normal in postmenopausal
osteoporosis, serum Mg, Cu, and Zn were more useful
for evaluation; (3) further studies are essential to evalu-
ate the role of dietary composition on the manifesta-
tions of osteoporosis; and (4) further studies are needed
to clarify the metabolic relationship between trace ele-
ments and calcitonin.
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