Is the measurement of serum testosterone routinely indicated in men with erectile dysfunction?

To investigate the usefulness of serum testosterone levels as a relevant or useful indicator of sexual potency in men attending an erectile dysfunction clinic.

Ninety consecutive men attending the erectile dysfunction clinic completed a sexual-activity questionnaire, and underwent a focused physical examination and questioning about their medical history. The serum testosterone level was measured in all patients and the results analysed in relation to the patient's age. Patients with low serum testosterone levels commenced replacement therapy comprising three intramuscular injections of testosterone (Sustanontrade mark, Organon, The Netherlands) 250 mg every third week. Potency status and serum testosterone were reassessed after 3 months' treatment.

Of the 90 men, 28 (31%) were aged < 50 years whilst 62 (69%) were >/=50 years old. Nineteen (21%) patients overall had low testosterone levels; four of these were < 50 and 15 were >/=50 years old. Five of 90 patients had a decreased libido; two of these also had low testosterone levels and all were < 50 years old. Testosterone levels returned to normal in all patients who received replacement therapy but potency returned in only two (10%); both were in the older group.

Measuring testosterone was not helpful in assessing potency or libido and low serum levels were not related to age. Correcting low testosterone did not improve either impotence or libido.