The relationship between plasma FSH, testosterone levels and testicular histology in males with azoospermia.

The plasma FSH and testosterone levels were determined by the radioimmunological method in 27 men with azoospermia. The plasma FSH levels were elevated in the Sertoli-cell only syndrome and in the case of inhibited spermatogenesis. The plasma FSH level was normal in patients with normal spermatogenesis. The plasma testosterone level did not differ from the normal values in any of the above-mentioned groups of patients.