Effects of intermission and resumption of long-term testosterone replacement therapy on body weight and metabolic parameters in hypogonadal in middle-aged and elderly men.

Objective: In addition to primary and secondary ('classical') hypogonadism, hypogonadism occurring in middle-aged and elderly men has been recognized. There is evidence that restoring T levels to normal improves body weight, serum lipids and glucose levels.

Design: Observational registry study.

Patients: Two hundred and sixty-two hypogonadal, middle-aged and elderly, men received testosterone replacement treatment (TRT). After having been on TRT for a mean duration of 65·5 months, TRT was temporarily intermitted in 147 patients for a mean of 16·9 months (Group I) due to cost reimbursement issues and in seven men due to prostate cancer. All these men resumed TRT for a mean period of 14·5 months. Of the cohort, 115 men were treated continuously (designated as Group C). To compare on-treatment to off-treatment periods, three periods of equal duration were defined: pre-intermission (on TRT), during intermission (off TRT) and post-intermission (on TRT after resumption of TRT). For proper comparison, the same periods were analysed for those patients who continued TRT throughout (Group C).

Measurements: Variables of body weight, glucose metabolism, lipids, blood pressure and C-reactive protein (CRP).

Results: In Group C there was a continuous improvement of body weight, serum lipids, glucose, HbA1c , blood pressure and CRP. In Group I there was a similar initial improvement which was reversed upon intermission of T administration but which appeared again when T treatment was reinstated.

Conclusions: Our observation indicates that T administration improves body weight and metabolic factors in men with hypogonadism but withdrawal of T reverses these beneficial effects to appear again when TRT is resumed.