E. Shane et al., BONE LOSS AND TURNOVER AFTER CARDIAC TRANSPLANTATION, The Journal of clinical endocrinology and metabolism, 82(5), 1997, pp. 1497-1506
Cardiac transplantation is associated with increased prevalence and in
cidence of fracture, and rapid bone loss has been reported during the
first posttransplant year. To define further the pattern and etiology
of bone loss after cardiac transplantation, we enrolled 70 patients (5
2 men and 18 women) in a prospective 3-yr study. Bone densitometry (BM
D) and biochemical indexes of mineral metabolism were performed before
and at defined times after transplantation. Despite supplementation w
ith elemental calcium (1000 mg/day) and vitamin D (400 IU/day), the me
an rate of bone loss during the first year was 7.3 +/- 0.9% (+/-SEM) a
t the lumbar spine and 10.5 +/- 1.1% at the femoral neck. The rate of
bone loss slowed (P < 0.001 compared to year I) at both sites (0.9 +/-
0.9% and 0.1 +/- 1.0%, respectively) during the second year. During t
he third year, lumbar spine BMD increased at a rate of 2.4 +/- 0.8%/yr
(P < 0.02 compared to year 2), but femoral neck BMD did not change. A
t the radius, the rate of decline in BMD was negligible during the fir
st year (0.9 +/- 0.5%), but was significant during the second (2.1 +/-
0.6%; P < 0.01) and third (2.9 +/- 0.8%; P < 0.03) years. Evaluation
of the pattern of bone loss during the first year demonstrated that me
an lumbar spine BMD decreased rapidly during the first 6 months, after
which there was no further decline. In contrast, femoral neck BRID co
ntinued to fall at an annualized rate of 8.2 +/- 1.3% during the secon
d half of the year. The pattern and rates of bone loss were similar in
men and women. Biochemistries revealed decreases in serum testosteron
e and osteocalcin and increases in all bone resorption markers 1 and 3
months after transplantation, with a return to baseline by 6 months.
Higher rates of bone loss were associated with greater exposure to pre
dnisone, lower serum concentrations of vitamin D metabolites, greater
suppression of osteocalcin, higher levels of bone resorption markers,
and, in men, lower serum testosterone concentrations. We conclude that
rapid bone loss is primarily confined to the initial year after trans
plantation. During the first 6 months, bone loss is accompanied by alt
erations in markers of bone turnover consistent with biochemical uncou
pling of bone formation and resorption. Greater exposure to glucocorti
coids, lower serum concentrations of vitamin D metabolites and testost
erone, and higher bone turnover were associated with more rapid bone l
oss.