Endocrine screening for sexual dysfunction using free testosterone determinations

Controversy exists concerning the need for routine endocrine screening in impotent men. Debate also continues as to what hormonal studies are necessary, the role of the free fraction of testosterone and whether a history of decreased libido or testicular atrophy can predict these endocrinopathies.

We reviewed 508 consecutive men who presented with sexual dysfunction within a 22-month period. Testosterone data were available for 268 patients (53%) and prolactin data were available for 170 (33%).

Hypogonadism, defined as 2 abnormal total testosterone levels, was found in 42 of our 268 patients (15.6%). A history of decreased libido by patient questionnaire and/or testicular atrophy on physical examination could not predict these cases. A normal free fraction of testosterone saved further unnecessary endocrine evaluation in 50% of patients with hypogonadism. Hypoprolactinemia was noted in 3 of 170 patients (1.8%).

Routine endocrine screening remains a necessary part of the evaluation for sexual dysfunction. A history of decreased libido and/or testicular atrophy on physical examination cannot predict hypogonadism. Measurement of free fraction of testosterone will further lessen unnecessary endocrine evaluations by 50% and should become standard practice in screening for hypogonadism. Prolactin levels are necessary only in patients with hypogonadism and/or a history of decreased libido.