Introduction: This is a four-year follow-up of 25 men who received parenteral testosterone undecanoate (TU), 1000 mg every 12 weeks for at least four years. This study was a continuation of a 30-week study wherein the effects of TU had been compared to those of parenteral testosterone enanthate.
Methods & results: Plasma testosterone (T) trough values of the injection interval of 12 weeks): median 11.9 - 15.9 nmol/L (N 10.0-30.0). E2 and SHBG were stable. Body weight, BMI, waist-to-hip ratio remained stable. Total cholesterol, and triglycerides were unchanged but plasma LDL declined while HDL, after an initial reduction over the first 30 weeks, had increased significantly after three years. Leptin levels, bone mineral density, blood pressure, liver function tests, haemoglobin and haematocrit levels remained stable without values above the upper limit of normal. Over the first 12 months of the study there was an increase in prostate volume from 19.7 +/- 8.8 mL to 22.0 +/- 8.4 mL (p < 0.05) but thereafter volumes remained stable, paralleled by an increase in PSA from 0.67 +/- 0.38 microg/dL to 0.75 +/- 0.35 microg/dL (p < 0.05) without any further changes after 12 months.
Conclusion: TU appears to be a stable and safe treatment modality of hypogonadal men.