Will Testosterone and Growth Hormone Improve Bone Structure?

Replacement of testosterone or growth hormone in patients who are deficient improves osteoporosis associated with these deficiencies. In some tissues, such as muscle, the effects of testosterone and growth hormone are additive, but it is not known if the effects are additive in bone as well. This study will compare the effects of testosterone alone with testosterone plus growth hormone in improving bone structure in men with total pituitary hormone deficiency. Participants in this study will be men who have pituitary or hypothalamic disease and have deficiencies of all pituitary hormones, but who have not been treated with either testosterone or growth hormone. The men will be randomly assigned to receive either testosterone alone or testosterone plus growth hormone for two years. Testosterone in a gel form will be applied daily to the skin. Growth hormone will be self-administered by daily subcutaneous injection. Blood concentrations of both hormones will be monitored with blood tests every 3 months during the 2-year study. Doses of the hormones will be adjusted to keep blood concentrations of the hormones within the normal range. Changes in bone structure will be assessed noninvasively before treatment and after one year and two years of treatment by magnetic resonance microimaging (µMRI) and dual energy X-ray absorptiometry (DEXA).