Gender Differences in Serum Markers of Bone Resorption in Healthy Subjects and Patients with Disorders Affecting Bone

To assess how two different serum markers of bone resorption may reflect changes in bone turnover, we compared age- and sex-related changes in serum C-terminal telopeptide of type I collagen (βCTx) and tartrate-resistant acid phosphatase activity (TRAP) in 136 healthy men and 184 normal women. Serum levels of the two markers were also assessed in several groups of patients of both sexes presenting with the most common metabolic and endocrine bone diseases: established osteoporosis (n= 77), primary hyperparathyroidism (n= 44), glucocorticoid excess (n= 17), chronic renal failure (n= 39), active Paget’s disease of bone (n= 5), humoral hypercalcemia of malignancy (n = 3), osteomalacia (n= 3), hyperthyroidism (n= 10), post-surgical hypoparathyroidism (n= 10), acromegaly (active disease, n= 8) and Cushing’s syndrome (n= 10). In men the regression of βCTx with age showed an initial decrease in bone resorption followed by an increase thereafter, starting from the sixth decade of life. No age-related change in serum TRAP activity was observed. In women, by contrast, a slight but significant linear correlation of both serum βCTx and TRAP with age (r= 0.223, p<0.003 and r= 0.333, p<0.0001, respectively) was found, the two markers being positively correlated (r= 0.238, p<0.002). In each class of patients the mean Z-scores of βCTx were significantly higher than those of TRAP activity. Moreover, compared with normal subjects, serum βCTx seems to be characterized by a superior sensitivity relative to TRAP measurement, at least in the disorders studied.