Isolated follicle-stimulating hormone deficiency in men: successful long-term gonadotropin therapy.

Two men with primary infertility after 6 to 11 years of marriage were found to have isolated follicle-stimulating hormone deficiency syndrome (IFDS). Their endogenous gonadotropin secretion was compared with that of two other infertile men with hypothalamic disease (Kallmann's syndrome) and pituitary tumor with hyperprolactinemia. Treatment with intramuscular gonadotropin was given to produce circulating and 24-hour urine levels of luteinizing hormone and follicle-stimulating hormone at or above the upper limit of the normal male range to ensure continued gonadal stimulation. Sperm counts increased in IFDS men within 6 to 26 weeks, with maximum total sperm counts of 33.5 and 20 million after 9 to 80 weeks. Pregnancy occurred after 20 weeks' therapy in one patient's wife with the subsequent delivery of a normal male infant. IFDS may be a treatable cause of male infertility given adequate gonadotropin therapy.