Inhibin B reference data for fertile and infertile men in Northeast America.

OBJECTIVE

To determine normative levels of inhibin B and examine levels in relationship to FSH, sperm count, and motility in a cohort of fertile and infertile men from the Northeast United States.

DESIGN

Prospective comparative study of inhibin B levels in fertile and infertile patient groups.

SETTING

Tertiary academic referral center.

PATIENT(S): Fertile men were recruited among those presenting for elective vasectomy. Men being evaluated for infertility were also recruited within the same practice.

INTERVENTION(S): Serum collection.

MAIN OUTCOME MEASURE(S): FSH and inhibin B levels were measured in serum samples.

RESULT(S): A total of 55 fertile and 85 presenting for infertility evaluations were recruited. The mean serum inhibin B level was significantly higher in the fertile (138 pg/mL) than infertile group (78 pg/mL). Inhibin B levels correlated positively (R(2) = 0.27) and FSH correlated negatively (R(2) = 0.33) with total sperm concentration. General linear model multiple regression demonstrated that the FSH and inhibin B were equally predictive of sperm concentration.

CONCLUSION(S): Inhibin B levels in fertile men and infertile men in Northeast America were similar but not identical to those reported in other geographic regions. Both inhibin B and FSH are useful markers of spermatogenesis.