RESUMEN
Background: Male infertility is responsible for 35 percent of infertile couples. Aim: To investigate the causes of male infertility and the relative importance of endocrine factors. Patients and methods: Patients referred to an andrology clinic due to an abnormal spermiogram were studied. A testitular examination, spermiogram and determination of FSH, LH, testosterone and prolactin were done to all. Testicular biopsy was done to patients with severe oligospermia or azoospermia. Causes of infertility were defined and classified as pretesticular, testicular, posttesticular or unclassified. Results: Two hundred fifty seven males were studied. In 3.5 percent of them, the cause of infertility was defined as pretesticular (that included hypothalamic and pituitary endocrine causes), in 66.9 percent it was classified as testicular, in 15.6 percent as posttesticular and in 14 percent, as unclassified. Thirty percent of infertility cases were idiopathic, 17.9 percent were associated to varicocele, 12.8 percent were associated to cryptorchidism, 8.9 percent to Klinefelter syndrome and 6.6 percent to exposure to toxic substances. In 50 percent of patients with cryptorchidism, this abnormality was found during the specialized andrological examination and referrals for surgical correction were made late. Two thirds of patients with Klinefelter syndrome were hypoandrogenic. Conclusions: Causes for male infertility should be investigated and diagnosed accurately. Primary hypoandrogenic testicular failures must be treated with hormone replacement therapy