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The Journal of Clinical Endocrinology & Metabolism
Copyright © 2000 by The Endocrine Society
Vol. 85, No. 5
Printed in U.S.A.
Prediction of Bone Mass Change after
Parathyroidectomy in Patients with Primary
Hyperparathyroidism*
DAIKI NAKAOKA, TOSHITSUGU SUGIMOTO, TATSUYA KOBAYASHI,
TORU YAMAGUCHI, AKIRA KOBAYASHI, AND KAZUO CHIHARA
Third Division, Department of Medicine, Kobe University School of Medicine (D.N., T.S., T.K., T.Y.,
K.C.), Kobe 650-0017; and Kuma Hospital (A.K.), Kobe 650-0011, Japan
ABSTRACT
A major challenge in the management of primary hyperparathyroidism (pHPT) is the decision regarding which patients should undergo parathyroidectomy (PTX), although the Consensus Development Conference of the NIH has proposed guidelines for the
indication of surgery. In the present study, changes in bone mineral
density (BMD) after PTX were compared between pHPT patients who
did and did not meet the NIH criteria, and we further tried to predict
the BMD change after PTX from preoperative parameters. The subjects were 44 pHPT patients (30 women and 14 men) who had had
successful PTX. Lumbar and radial BMD were measured before and
1 yr after PTX by dual energy x-ray absorptiometry and single photon
absorptiometry, respectively. Average annual percent increases in
lumbar and radial BMD after PTX were 12.2 ⫾ 1.4% and 11.6 ⫾ 1.6%
(mean ⫾ SEM), respectively, and those net increases were 0.0803 ⫾
0.0008 and 0.0484 ⫾ 0.0006 g/cm2, respectively. There were no significant differences in percent or net changes in either radial or
lumbar BMD after PTX between the groups divided according to each
of the NIH criteria, such as age (ⱖ50 and ⬍50 yr), serum calcium level
(ⱖ12 and ⬍12 mg/dL) or the existence of urinary stones (presence and
P
RIMARY HYPERPARATHYROIDISM (pHPT), a relatively common endocrine disorder, is now recognized
as a disorder with few overt manifestations, presenting most
often as asymptomatic hypercalcemia. Parathyroidectomy
(PTX) is the only option available for the cure of pHPT. The
Consensus Development Conference of the NIH proposed
guidelines for the surgical indication of pHPT (1). These
include 1) serum calcium (Ca) above 12 mg/dL, 2) marked
hypercalciuria (⬎400 mg/g creatinine䡠day), 3) any overt
manifestations of pHPT (nephrolithiasis, osteitis fibrosa cystica, or classical neuromuscular diseases), 4) markedly reduced cortical bone density (z-score, below ⫺2), 5) reduced
creatinine clearance in the absence of other causes, and 6) age
less than 50 yr. In the United States, only about half of the
patients meet one or more of these criteria for the surgical
indication (2). PTX seems beneficial to pHPT patients, as
Received May 5, 1999. Revision received January 12, 2000. Accepted
February 7, 2000.
Address all correspondence and requests for reprints to: Toshitsugu
Sugimoto, M.D., Third Division, Department of Medicine, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 6500017, Japan.
* This work was supported in part by Smoking Research Foundation
and the Research Society for Metabolic Bone Disease (to T.S.) and by
Research Society for Metabolic Bone Disease and Health Sciences Research grants.
absence). On the other hand, when the subjects were divided on the
basis of radial BMD (above and below a z-score of ⫺2), the annual
percent and net increases in lumbar BMD and percent increase in
radial BMD after PTX were significantly higher in the group with the
lower z-score. Next, patients were divided into two groups with and
without the indication of PTX based on NIH guidelines. Twenty-nine
patients had the surgical indication by meeting one or more of these
criteria and 15 patients had no indication without meeting any of the
criteria. There were no significant differences between the two groups
in annual percent or net changes in radial or lumbar BMD after PTX.
A stepwise multiple regression analysis revealed that serum alkaline
phosphatase level and the severity of cortical bone mass reduction
were the best predictors of both percentage and net changes in lumbar
BMD, with high determination coefficients (r2 ⬎ 0.7). In conclusion,
a considerable increase in BMD could be obtained after PTX even in
patients without surgical indication from the NIH. Alkaline phosphatase and the severity of cortical bone mass reduction are clinically
useful for predicting the changes in lumbar BMD after PTX. The
present findings provide a useful clue for the indication of surgery in
pHPT. (J Clin Endocrinol Metab 85: 1901–1907, 2000)
there have been several reports documenting a postoperative
increase in bone mineral density (BMD) (3, 4). In contrast,
there is also substantial evidence that most cases of pHPT are
not progressive and that conservative management of pHPT
patients does not lead to progression of the disease (5). Therefore, the validity of PTX has been questioned, and it remains
unclear which pHPT patients should be subjected to PTX. In
this respect, it would be clinically useful if BMD changes after
PTX could be predicted from preoperative parameters.
In the present study BMD changes after PTX were compared between pHPT patients who did and did not meet NIH
criteria, and we further proposed a means for predicting the
changes in BMD after PTX from various preoperative
parameters.
Subjects and Methods
Subjects
Sixty-nine patients had been hospitalized in Kobe University Hospital
from 1989 to 1997. Thirty-seven patients (54%) were asymptomatic. PTX
was recommended to all pHPT patients whose abnormal parathyroid
glands were successfully identified by image techniques and who had
no serious complications regardless of whether patients met the surgical
indications of the NIH. Several patients either refused operation or were
unable to undergo surgery because of serious complication such as
cardiac dysfunction. Of those operated, we retrospectively and consecutively evaluated 44 patients who had been followed with biochemical
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NAKAOKA ET AL.
and BMD measurements at least 1 yr after PTX. The 44 patients (age, 56 ⫾
3 yr; mean ⫾ sem) included 14 men (mean age, 54 yr) and 30 women
(mean age, 58 yr). Twenty-two patients (50%) were postmenopausal
women not receiving any therapy for osteoporosis, including estrogen
replacement or bisphosphonate. Twenty-six patients (59%) had asymptomatic pHPT. Sixteen patients (36%) had a history of urinary stones.
Twenty-nine patients (66%) fulfilled 1 or more of the following accepted
surgical criteria from NIH: age 50 yr or younger (n ⫽ 10; 23%), serum
Ca level above 12 mg/dL (n ⫽ 8; 18%), history of nephrolithiasis (n ⫽
16; 36%); z-score at the radius of ⫺2 or lower (n ⫽ 14; 32%), and classic
neuromuscular signs of pHPT (n ⫽ 0; 0%). Baseline indexes are shown
in Table 1. All data were compatible with the existence of pHPT. All
subjects were successfully operated upon, with removal of their abnormal parathyroid glands, and biochemical values such as serum concentrations of Ca, phosphorus (P), alkaline phosphatase (ALP), midregion
PTH, and intact PTH returned to normal levels 1 yr after PTX as previously reported (6, 7) (Table 1). Surgical pathology showed adenoma
in 37 (84%) and hyperplasia in 7 patients (16%). None of them had
hepatic or renal dysfunction or other metabolic diseases that might cause
changes in bone metabolism. No subjects were taking drugs known to
influence bone or Ca metabolism, such as supplemental calcium, vitamin
D, estrogen, or bisphosphonate, before operation and during 1 yr postoperative period, except for 2 patients who received short-term supplementation of calcium because of severe hungry bone syndrome. The
clinical and biochemical data were obtained by reviewing the chart
records at admission, by questionnaires, or by interviews. Some missing
information was requested by letters sent to some patients. This study
was approved by the ethical review board of Kobe University Hospital.
The subjects agreed to participate in this study and gave informed
consent for monitoring biochemical markers and BMD after PTX.
Biochemical measurements
Serum concentrations of Ca, P, and ALP were measured by automated techniques at the central laboratory of Kobe University Hospital
(normal range: Ca, 8.5–9.9 mg/dL; P, 2.4 – 4.5 mg/dL; ALP, 100 –303
IU/L). Intact PTH and midregion PTH were measured by immunoradiometric assay (Allegro Intact PTH RIA kit, Nichols Institute Diagnostics, San Juan Capistrano, CA; normal range, 10 – 65 pg/mL) (8, 9) and
RIA (Yamasa hypersensitive PTH-RIA kit, YAMASA Shoyu Co. Ltd.,
Tokyo, Japan; normal range, 160 –520 pg/mL) (10), respectively. The
intact PTH RIA kit only reacts with human (h) PTH-(1– 84), whereas
hPTH-(1–34), hPTH-(39 – 84), and hPTH-(39 – 68) are nonreactive (11).
The Yamasa PTH-RIA kit consists of chicken PTH antiserum raised by
Hruska et al., 125I-labeled [Tyr43]hPTH-(44 – 68) as a radioligand, and
TABLE 1. Comparison of various indexes between preoperative
and 1 yr postoperative states in patients with primary
hyperparathyroidism
Age (yr)
Ca (mg/dL)
P (mg/dL)
ALP (IU/L)
Intact PTH (pg/mL)
Midregion PTH (pg/mL)
Radial BMD (g/cm2)
Lumbar BMD (g/cm2)
z-Score of radial BMD
z-Score of lumbar BMD
t-Score of radial BMD
t-Score of lumbar BMD
Preoperative
Postoperative
57.4 ⫾ 1.5
11.4 ⫾ 0.15
2.6 ⫾ 0.1
489 ⫾ 67
245 ⫾ 44
3002 ⫾ 482
0.468 ⫾ 0.020
0.705 ⫾ 0.026
⫺1.63 ⫾ 0.34
⫺0.76 ⫾ 0.14b
⫺5.51 ⫾ 0.60
⫺2.53 ⫾ 0.28d
58.4 ⫾ 1.5
9.0 ⫾ 0.05a
3.4 ⫾ 0.1a
238 ⫾ 9a
41 ⫾ 5a
435 ⫾ 90b
0.511 ⫾ 0.020a
0.787 ⫾ 0.029a
⫺1.12 ⫾ 0.34
⫺0.55 ⫾ 0.15c
⫺4.57 ⫾ 0.54
⫺2.09 ⫾ 0.26c
All data are presented as the mean ⫾ SEM. The z-score is the
number of SDs a given measurement differs from the mean for a sexand age-matched reference population. The t-score is the number of
SDs a given measurement differs from the mean for a normal young
adult reference population.
a
P ⬍ 0.01 compared with preoperative values.
b
P ⬍ 0.05 compared with z-score of radial BMD.
c
P ⬍ 0.05 compared with preoperative values.
d
P ⬍ 0.01 compared with t-score of radial BMD.
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synthetic hPTH-(1– 84) as a standard (12). This assay recognizes the
fragments containing at least the amino acid sequence of 44 – 68 in the
PTH molecule and intact PTH as well.
BMD measurements
BMD measurements were performed before and 1 yr after PTX.
Lumbar spine BMD was measured by dual energy x-ray absorptiometry
(QDR-1000, Hologic, Inc., Waltham, MA). BMD of the lumbar spine at
L2–L4 was measured separately and expressed as the mean. As vertebral
fractures may cause aberrations in BMD, data from fractured vertebrae
were excluded. Bone mineral content, bone width, and BMD (defined as
bone mineral content/bone width) were measured at the distal one third
of the radius using single photon absorptiometry (Bone Mineral Analyzer Type 278 O, Norland Corp., Fort Atkinson, WI). The coefficients
of variation (precision) in BMD measurements of the lumbar spine and
radius by our methods were 0.9% and 1.9%, respectively. The z-score is
the number of sds a given measurement differs from the mean for a sexand age-matched reference population. The t-score is the number of sds
a given measurement differs from the mean for a normal young adult
reference population.
Statistical analysis
All data were expressed as the mean ⫾ sem for each index. A regression analysis was performed using the statistical computer program
Abacus Concepts StatView (Abacus Concepts, Inc., Berkeley, CA). A
simple regression analysis was used to assess the linear relationship
between various parameters, and then Pearson’s correlation coefficients
were calculated. To determine which variables in the preoperative state
were independently and significantly associated with BMD changes in
the radius and lumbar spine after PTX, a stepwise multiple regression
analysis was performed. P ⬍ 0.05 was considered significant.
Results
Clinical characteristics in preoperative and
postoperative states
As shown in Table 1, all patients had elevated serum levels
of Ca and PTH. Elevated serum ALP levels indicated that
bone turnover was accelerated. Baseline z- and t-scores of
lumbar spine BMD were significantly higher than those of
radial BMD. Biochemical values, such as serum Ca, P, ALP,
midregion PTH, and intact PTH, returned to normal levels 1
yr after PTX. On the other hand, radial and lumbar BMD
values remained lower than normal 1 yr after PTX, judging
from their z-scores.
Comparison of changes in BMD after PTX between groups
who did and did not meet criteria of NIH guidelines
The annual percent increases in lumbar and radial BMD
after PTX were 12.2 ⫾ 1.4% and 11.6 ⫾ 1.6% (mean ⫾ sem),
respectively, and their net increases were 0.0803 ⫾ 0.0008 and
0.0484 ⫾ 0.0006 g/cm2, respectively. We divided pHPT patients into two groups according to each of the NIH criterion
and compared the annual percent changes in radial and
lumbar BMD after PTX. There were no significant differences
in percent or net changes in either radial or lumbar BMD after
PTX between two groups based on age (ⱖ50 and ⬍50 yr),
serum Ca level (ⱖ12 and ⬍12 mg/dL), or the existence of
urinary stones (presence and absence; data not shown). On
the other hand, as shown in Fig. 1, annual percent and net
increases in lumbar BMD and annual percent increases in
radial BMD after PTX were significantly higher in groups
with a z-score of radial BMD below ⫺2 than in groups with
the z-score of ⫺2 or more.
BONE MASS IN PRIMARY HYPERPARATHYROIDISM
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FIG. 1. Comparison of annual percent
and net changes in BMD after PTX between two groups divided according to a
NIH criterion for cortical bone density
(z-score at the radius, below ⫺2). Annual percent and net increases in lumbar BMD and annual percent increases
in radial BMD after PTX were significantly higher in the group with a z-score
of radial BMD below ⫺2, than in a group
with a z-score of ⫺2 or more.
TABLE 2. Comparison of baseline indexes between patients undergoing parathyroidectomy with and without the surgical indication
judged from NIH guideline
Age (yr)
Ca (mg/dL)
P (mg/dL)
ALP (IU/L)
Intact PTH (pg/mL)
Midregion PTH (pg/mL)
BUN (pg/mL)
Creatinine (mg/dL)
Creatinine clearance (mL/min)
z-Score of radial BMD
z-Score of lumbar spine BMD
Met
Not met
29
55.9 ⫾ 2.8
11.6 ⫾ 0.3
2.51 ⫾ 0.11
534 ⫾ 98
271 ⫾ 64
3574 ⫾ 694
16.6 ⫾ 1.3
0.89 ⫾ 0.08
71.9 ⫾ 9.0
⫺2.15 ⫾ 0.42
⫺0.65 ⫾ 0.17
15
60.2 ⫾ 1.5
10.9 ⫾ 0.1
2.70 ⫾ 0.13
396 ⫾ 34
192 ⫾ 36
1942 ⫾ 392
15.8 ⫾ 0.8
0.69 ⫾ 0.03a
88.1 ⫾ 9.2
⫺0.58 ⫾ 0.47a
⫺0.99 ⫾ 0.23
Normal range
8.4–9.9
2.4– 4.5
100–303
10– 65
160–520
9–22
0.5–1.3
All data were presented as the mean ⫾ SEM. Met, The group of patients that met one or more NIH guidelines; Not met, the group of patients
that did not meet any of NIH guidelines.
a
P ⬍ 0.05.
Next, all pHPT patients were divided into two groups with
or without the indication of PTX based on NIH guidelines.
Twenty-nine patients had surgical indication by meeting 1 or
more of these criteria (the Met group), and 15 patients had
no indication without meeting any criteria (the Not met
group). There were no significant differences between the 2
groups in baseline indexes such as age; serum levels of Ca,
P, ALP, or PTH; creatinine clearance; or z-scores of radial or
lumbar BMD, except for a significantly higher serum creatinine level in the Met group (Table 2). As shown in Fig. 2,
there were no significant differences between the 2 groups in
annual percent or net changes in either radial or lumbar BMD
after PTX, which indicated that a considerable increase in
BMD could be obtained after PTX even in patients without
surgical indication from the NIH.
We also divided patients into asymptomatic and symp-
tomatic groups and compared annual percent and net increases in radial and lumbar BMD after PTX. We found no
difference in percent or net BMD changes at either site between the two groups (data not shown).
Prediction of BMD changes after PTX
Figure 3 shows the relationships between various indexes
and annual percent changes in radial as well as lumbar BMD
after PTX. The annual percent change in lumbar BMD was
positively and significantly correlated with intact PTH,
midregion PTH, and ALP and was negatively and significantly correlated with the z-score of radial BMD, but not with
the z-score of lumbar BMD. In contrast, the annual percent
change in radial BMD was significantly and negatively correlated only with the z-score of radial BMD. The similar
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FIG. 2. Comparison of annual percent
and net changes in BMD after PTX between groups with and without the indication of PTX based on the NIH guidelines. Met, The group of patients who
met one or more NIH guidelines. Not
Met, The group of patients who did not
meet any of the NIH guidelines. There
were no significant differences between
the two groups in annual percent or net
changes in either radial or lumbar BMD
after PTX.
correlations were also observed between each parameter and
annual net changes in lumbar or radial BMD. The annual net
change in lumbar BMD was positively and significantly correlated with intact PTH (r ⫽ 0.664; P ⬍ 0.0001), midregion
PTH (r ⫽ 0.554; P ⬍ 0.0001), and ALP (r ⫽ 0.702; P ⬍ 0.0001)
and was negatively and significantly correlated with the
z-score of radial BMD (r ⫽ ⫺0.606; P ⫽ 0.0001), but not with
the z-score of lumbar BMD. In contrast, the annual net
change in radial BMD was significantly and negatively correlated only with the z-score of radial BMD (r ⫽ ⫺0.310; P ⬍
0.05; graphical data not shown). Next, we tried to predict the
annual percent and net changes in radial and lumbar BMD
after PTX from various indexes in the preoperative state,
such as age; serum levels of Ca, P, ALP, intact PTH, and
midregion PTH; as well as the z-scores of radial and lumbar
BMD. Table 3 shows stepwise multiple regression equations
describing the annual percent and net changes in radial and
lumbar BMD after PTX. As for BMD at the radius, the
midregion PTH and radial z-score were selected for the percent change, and the radial z-score and age were selected for
the net change, with relatively lower determination coefficients based on the analysis (r2 ⫽ 0.356 and 0.338, respectively). As for BMD at the lumbar spine, ALP and the radial
z-score were selected for the percent change, and ALP, radial z-score, and age were selected for the net change, with
higher determination coefficients (r2 ⫽ 0.725 and 0.789,
respectively).
Discussion
There have been several lines of evidence from densitometric studies showing that the reduction of cortical and
cancellous bone mass is at least partially reversible after PTX
(4, 13–15), although Hesp et al. reported no increase in cortical
bone 1–2 yr after PTX (16). However, no data are available
about BMD changes after PTX in pHPT patients with few
overt manifestations who did not meet any of the NIH criteria. In the present study, although both lumbar and radial
BMD values increased more markedly after PTX in a subset
of patients with severe reduction in radial bone mass (zscore, below ⫺2), considerable annual percent increases in
radial and lumbar BMD were still obtained in patients with
less severe reduction in cortical bone mass (z-score, ⫺2 or
more). The present study also showed that considerable increases in BMD at each site could be obtained even in patients
with mild or moderate serum Ca levels (⬍12 mg/dL) or
without symptoms related to pHPT. Moreover, no differences were found in annual percent or net changes in radial
or lumbar BMD after PTX between the Met and the Not met
groups or between asymptomatic and symptomatic patients.
The present findings indicate for the first time that PTX is
beneficial for bone mass even in patients without overt manifestations who do not meet any of the NIH criteria for
surgery. Thus, these results provide a useful clue for the
indication of surgery in pHPT. To our knowledge, there have
been no previous studies on how to predict the extent of
increase in bone mass using preoperative parameters. In this
study the stepwise multiple regression analysis showed that
the serum ALP level and radial z-score could be used to
predict the extent of increase in lumbar BMD. The equation
showing the relationship between the two indices and the
annual BMD increase at the lumbar spine gave a high determination coefficient and thus seems to be clinically useful.
BONE MASS IN PRIMARY HYPERPARATHYROIDISM
FIG. 3. Relationships between annual
percent changes in BMD after PTX and
various indices. The annual percent
change in lumbar BMD was positively
and significantly correlated with intact
PTH, midregion PTH, and ALP and was
negatively and significantly correlated
with the z-score of radial BMD, but not
with the z-score of lumbar BMD. In contrast, the annual percent change in radial BMD was significantly and negatively correlated only with the z-score of
radial BMD.
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NAKAOKA ET AL.
TABLE 3. Multiple regression equations describing percent and net changes in BMD of radius and lumbar spine after PTX
BMD
Lumbar spine
% Change
Net change
Radius
% Change
Net change
P
r2
⬍0.0001
0.725
⬍0.0001
0.789
11.0
⫺0.001 ⫻ midregion PTH
⫺2.4 ⫻ z-score of radial BMD
⬍0.01
0.356
0.117
⫺0.009 ⫻ z-score of radial BMD
⫺0.001 ⫻ age
⬍0.01
0.338
Equation
5.2
⫹0.01 ⫻ ALP
⫺1.16 ⫻ z-score of radial BMD
0.07
⫹6.6 ⫻ 10⫺5 ⫻ ALP
⫺0.008 ⫻ 10⫺6 ⫻ z-score of radial BMD
⫺0.001 ⫻ age
Independent variables are age, serum Ca, P, ALP, intact PTH, midregion PTH, percent TRP, z-score of radial BMD, and z-score of lumbar
BMD.
The present study also provides novel information concerning the prediction of BMD changes after PTX from preoperative parameters.
Cortical bone is predominant in the distal one third of the
radius, whereas cancellous bone is rich in the lumbar spine.
In the present study the reduction of radial BMD was more
prominent than that of lumbar BMD, indicating the preferential reduction of cortical bone mass in the patients. The
present data are compatible with previous findings that most
pHPT patients had reduced cortical BMD in the face of relatively preserved cancellous BMD (17–22). This phenomenon is thought to be partly explained by the anabolic action
of PTH on cancellous bone (23–25). In addition, this study
showed that the increase in lumbar BMD, but not the increase
in radial BMD, was positively correlated with preoperative
serum levels of ALP and PTH, suggesting that abrupt reduction in a circulating PTH level also affects cortical and
cancellous bones in different manners. Alternatively, as serum ALP is a marker for the bone turnover rate, this finding
suggests that higher preoperative bone turnover rate augments the recovery of cancellous bone mass after PTX.
In the present study the extent of the increases in both
lumbar and radial BMD after PTX was negatively correlated
with the preoperative z-score of radial BMD, namely the
extent of the increases in BMD at each site after PTX was
higher in patients with the greatest reduction in preoperative
radial BMD, as previously shown by Silverberg et al. (4). In
contrast, such a relationship was not found between the
extent of the increases in BMD at each site after PTX and the
preoperative z-score of lumbar BMD, implying that a similar
degree of BMD increase was obtained regardless of the severity of preoperative reduction in lumbar bone mass. The
present study also revealed that there was no difference in
the overall percent increase in BMD between the radius and
the lumbar spine after PTX. These findings were somewhat
different from those of Silverberg et al., who reported that the
patients most severely affected at the lumbar spine had the
greatest response to PTX (26), and that the percent increase
in lumbar BMD after PTX was greater than that in radial
BMD (4). This discrepancy might be partly explained by
more severe states of hyperparathyroidism and radial BMD
reduction in our subjects, judging by higher serum levels of
PTH and ALP as well as a higher population with z-score at
the radius of ⫺2 or lower compared with those documented
in their study (4). Alternatively, some racial differences
might exist in the reversibility of cortical bone after PTX,
because the data obtained from Caucasian patients with classical pHPT showed no or only modest improvements at the
cortical site (13–16).
Biochemical and bone densitometric indexes have shown
that conservative management of pHPT patients is not associated with progression of the disease (5). We also found
long term stable biochemical parameters and BMD values in
conservatively managed patients. Thus, it is possible that the
hyperparathyroid state provides some ongoing protection
from the expected bone loss. Nonetheless, this study shows
that PTX brings about increases in radial and lumbar BMD
values as much as approximately 10% in virtually all pHPT
patients, including postmenopausal women. This is in sharp
contrast with the well known fact that bone loss caused by
postmenopausal osteoporosis is difficult to satisfactorily restore. As pHPT predominantly affects women and occurs
frequently during the postmenopausal period (27), it may be
beneficial to recommend PTX, particularly in postmenopausal women who could not otherwise obtain such a large
increase in bone mass.
This study has some limitations. First, the sample size was
not large enough to make definite conclusions. Second, in Japan, the percentage of pHPT patients who are asymptomatic is
not as high as in the United States (28). However, subjects
admitted to Kobe University Hospital, a tertiary care center,
might have a relatively severe pathological state of pHPT. It is
therefore possible that patients enrolled in this study were not
representative of Japanese pHPT patients. Third, we presented
only preoperative and 1 yr postoperative data. Therefore, the
time course of changes in BMD and biochemical data could not
be determined from these limited results.
In conclusion, the serum ALP level and the severity of
cortical bone mass reduction are clinically useful indices for
predicting the extent of increase in lumbar BMD after PTX.
A considerable increase in BMD was obtained after PTX even
in patents without severe reduction of bone mass as well as
BONE MASS IN PRIMARY HYPERPARATHYROIDISM
in patients who did not meet any criteria for the surgical
indication from NIH.
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