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The utility of alkaline phosphatase as a marker for response to testosterone replacement therapy in hypogonadal men

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Sources of Funding: None

Introduction

Osteopenia and osteoporosis may be adverse sequelae of hypogonadism. In a recent publication, Dabaja, et al (2015) found elevated alkaline phosphatase (AP) in men with total testosterone (T) <250ng/dl, suggesting increased bone turnover. Following T therapy, decreased AP was associated with increased bone mineral density, suggesting that AP levels may be used as a marker of response to T therapy. We evaluated the association between T and AP levels in an outpatient setting in an effort to replicate these findings.

Methods

A retrospective chart review of 88 men who presented to our reproductive medicine clinic with symptomatic or clinical features of hypogonadism was performed. Men with total testosterone levels <350ng/dL were followed for 2 years with AP levels measured at baseline, 6, 12, and 24 months. 15 of the 88 men had both T and AP measured before treatment, and at 6, 12, and 24 months. Men were either treated with transdermal testosterone, intramuscular testosterone, or testosterone long-acting pellets._x000D_

Results

Mean age (SD) of the patients was 61 (18) years, with an age range of 27 to 84. The mean (SD) testosterone level was 217 (75) ng/dL at baseline and 675 (538), 652 (373), 716 (516) ng/dL at 6, 12, and 24 months, respectively. AP levels decreased from a mean (SD) of 67 (14) U/L to 65 (14) U/L (P=0.353), 65 (12) U/L (P=.421), and 61 (14) U/L (P=.111), at 6, 12, and 24 months respectively._x000D_

Conclusions

We found no correlation between testosterone replacement therapy and AP levels. Specifically, the significant decrease in AP levels following T therapy noted in the Dabaja study were not observed in this small cohort. There were significant differences between the two studies, including mean age (41 vs 61 years), mean initial level of AP (87 u/L vs 67 u/L), mean decrease in AP after two years of treatment (32 u/L vs 6 u/L), and mean testosterone level prior to treatment (264 ng/dL vs 217 ng/dL). The significant age difference between the two studies is noteworthy, suggesting that younger patients may be more susceptible to increased bone turnover as a result of T deficiency. Further investigation may be needed to determine whether AP can be used as a marker of response to T replacement therapy in a select group of patients._x000D_

Funding

None

Authors
John Sheng
Ari Sapin
Michael Benson
Hossein Sadeghi-Nejad
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