Serum FSH and spermatogenesis

Between August, 1981 and May, 1983 (21 months), 371 men were evaluated for hypofertility. Data from semen analyses, testicular biopsies, and pooled serum FSH (RIA) were analysed. FSH levels were investigated in 204 patients. Bilateral testicular biopsies were performed on 104 patients. FSH was found to be elevated in 18 of 30 patients (60%) who were azoospermic. 10 of47 (47%) with less than 20X106 ejaculated sperm, and 7 of 56 (12.5%) patients with 20–50 X106 sperm per ejaculate. No patients with more than 50 X106 sperm per ejaculate (n = 74) had an elevated FSH. Serum FSH does not seem warranted in patients with more than 50 X106 sperm per ejaculate (or 15 X106 sperm per ml). Testicular biopsies, analysed by spermatid quantitation were frequently very abnormal (25.6%) despite normal FSH levels, indicating a failure of hypothalamic/pituitary response to hypospermatogenesis. Conversely, testicular biopsies were ‘normal’ in 36% of severely oligospermic men (≤10 X106 sperm/ejaculate) indicating potentially reconstructible lesions.