• A total testosterone level below 250 nanograms/mL is associated with decreased sexual function and osteoporosis.
• It is possible that as many as 5 to 50 per cent of older men would be candidates for testosterone replacement therapy.
• Most studies have shown a small increase in lean body mass and bone mineral density and a reduction of fat mass with testosterone replacement.
• It is possible that testosterone replacement may be favourable as far as heart disease is concerned, but unfavourable in regard to prostate cancer.
• Further studies are urgently required to determine if testosterone replacement therapy increases the risk of prostate cancer and benign prostatic hypertrophy (enlarged prostate). It is also possible that it could increase the level of prostate specific antigen (PSA) with the possible consequence of unnecessary biopsies and surgery.
• If testosterone replacement therapy is warranted it should be administered in the form of a gel or patch.

Report of National Institute on Aging Advisory Panel on Testosterone Replacement in Men. Journal of Clinical Endocrinology and Metabolism, Vol. 86, October 2001, pp. 4611-14