The effect of hypogonadism and testosterone-enhancing therapy on alkaline phosphatase and bone mineral density.
Academic Article
Overview
abstract
OBJECTIVE: To evaluate the relationship of testosterone-enhancing therapy on alkaline phosphatase (AP) in relation to bone mineral density (BMD) in hypogonadal men. PATIENTS AND METHODS: Retrospective review of 140 men with testosterone levels of <350 ng/dL undergoing testosterone-enhancing therapy and followed for 2 years. Follicle-stimulating hormone, luteinising hormone, free testosterone, total testosterone, sex hormone binding globulin, calcium, AP, vitamin D, parathyroid hormone, and dual-energy X-ray absorptiometry (DEXA) scans were analysed. A subgroup of 36 men with one DEXA scan before and one DEXA 2 years after initiating treatment was performed. RESULTS: Analysis of the relationship between testosterone and AP at initiation of therapy using stiff linear splines suggested that bone turnover occurs at total testosterone levels of <250 ng/dL. In men with testosterone levels of <250 ng/dL, there was a negative correlation between testosterone and AP (R(2) = -0.347, P < 0.001), and no correlation when testosterone levels were between 250 and 350 ng/dL. In the subgroup analysis, the mean (sd) testosterone level was 264 (103) ng/dL initially and 701 (245), 539 (292), and 338 (189) ng/dL at 6, 12, and 24 months, respectively. AP decreased from a mean (sd) of 87 (38) U/L to 57 (12) U/L (P = 0.015), 60 (17) U/L (P < 0.001), and 55 (10) U/L (P = 0.03) at 6, 12, and 24 months, respectively. The BMD increased by a mean (sd) of 20 (39)% (P = 0.003) on DEXA. CONCLUSION: In hypogonadal men, the decrease in AP is associated with an increase in BMD on DEXA testing. This result suggests the use of AP as a marker of response to therapy.
