Differential effects of endocrine dysfunction on the axial and the appendicular skeleton

In 100 patients with various types of endocrine dysfunction, we measured bone mineral density (BMD) at the midradius (greater than 95% cortical bone) and distal radius (75% cortical and 25% trabecular bone) by single photon absorptiometry and at the lumbar spine (greater than 66% trabecular bone) using the new technique of dual photon absorptiometry. BMD in each endocrine disorder deviated in at least one site from the sex-specific age regression of 187 normal subjects. For patients with primary hyperparathyroidism, hypercortisolism, and hyperthyroidism this deviation was negative (suggesting bone loss), whereas for patients with secondary hyperparathyroidism due to chronic renal failure, acromegaly, and postsurgical hypoparathyroidism it was positive (suggesting bone gain). When all six states of endocrine dysfunction were compared concomitantly by multivariate analysis of variance, the profile of the changes in BMD differed significantly (P less than 0.001), indicating a nonuniform response of bone to the various hormonal alterations. When values for BMD at each of the three scanning sites were compared the midradius and distal radius did not differ significantly; either of the radius measurements, however, differed significantly (P less than 0.001) from the lumbar spine. Thus, the BMD of the axial skeleton cannot be reliably predicted from measurements made in the appendicular skeleton. We conclude that the effects of endocrine dysfunction on bone density are complex and are both disease and site specific.