ROLE OF ESTROGEN DEFICIENCY IN PATHOGENESIS OF SECONDARY HYPERPARATHYROIDISM AND INCREASED BONE-RESORPTION IN ELDERLY WOMEN

Whether the increased bone resorption and secondary hyperparathyroidis m in elderly women is due to aging or to estrogen deficiency is unclea r. To address this issue, we measured serum intact parathyroid hormone (PTH) and biochemical markers in serum and urine samples from 30 prem enopausal women (32 +/- 0.5 years, mean age +/- SE), 30 estrogen-defic ient postmenopausal women (74.2 +/- 0.6 years), and 30 elderly women ( 73.8 +/- 0.6 years) receiving long-term estrogen treatment. Because th e first and third groups were comparable in estrogen status but not in age, whereas the second and third groups were comparable in age but n ot in estrogen status, the independent effects of age and estrogen def iciency could be assessed quantitatively. Mean values were higher in t he estrogen-deficient postmenopausal women than in the premenopausal w omen for serum PTH (by 33%, p < .01) and for bone resorption markers [ by 50% (p < .001) for urine cross-linked N-teleopeptide of type I coll agen (NTx); 34% (p < .001) for urine pyridinoline (Pyd); and 36% (p < .001) for urine deoxypyridinoline (Dpd)]. However, mean values for ser um PTH in the postmenopausal women receiving estrogen treatment did no t differ from those in the premenopausal women, and mean values for bo ne resorption markers were not different !urine NTx and Pyd) or were l ower [urine Dpd, by -12%, (p < .005)]. These findings suggest that lat e consequences of estrogen deficiency rather than age-related processe s per se are the principal causes of the secondary hyperparathyroidism and increased bone resorption in elderly women.