Background: Loss of muscle mass (sarcopenia) leads to frailty in older men. The decline in testosterone over the life span may contribute to this muscle loss. We studied the ability of oral testosterone to prevent muscle loss in older men over a 12-month period.
Methods: A standard dose (80 mg twice daily) of testosterone undecanoate or placebo was administered for 1 year to 76 healthy men aged 60 years or older. All men had a free testosterone index of 0.3-0.5, which represents a value below the normal lower limit for young men (19-30 years), but remains within the overall normal male range. Measurements of body composition, muscle strength, hormones, and safety parameters were obtained at 0, 6, and 12 months.
Results: Lean body mass increased (p =.0001) and fat mass decreased (p =.02) in the testosterone as compared with the placebo-treated group. There were no significant effects on muscle strength. There was a significant increase in hematocrit (0.02%) in the testosterone-treated group (p =.03). Plasma triglycerides, total cholesterol, and low-density lipoprotein cholesterol levels were similar in both groups, but there was a decrease in high-density lipoprotein cholesterol (-0.1 mmol/L) at 12 months in the testosterone group as compared to the placebo group (p = 0.026). There were no differences in prostate-specific antigen or systolic or diastolic blood pressure between the groups.
Conclusion: Oral testosterone administration to older relatively hypogonadal men results in an increase in muscle mass and a decrease in body fat.