Bioactive and immunoreactive FSH in serum of normal and oligospermic men.

In men suffering from idiopathic oligospermia and azoospermia the hypothesis was tested that decreased spermatozoa production could be due in part to inadequate hormonal stimulation of spermatogenesis. In 53 healthy male subjects with normal spermatozoa production (n = 10), varying degrees of oligospermia (n = 40), and azoospermia (n = 3), serum immunoreactive LH, testosterone (T), and oestradiol (E2), and immunoreactive and bioactive FSH concentrations were determined. FSH bioactivity was estimated using the rat granulosa cell aromatase bioassay. Mean LH, T, and E2 levels were similar in the control group (spermatozoa concentration greater than 40 x 10(6)/ml) compared with men exhibiting mild (10-20 x 10(6)/ml), moderate (5-10 x 10(6)/ml), or severe oligospermia (1-5 x 10(6)/ml), and in the azoospermia group. An inverse correlation was found between immunoreactive FSH levels and spermatozoa concentration (P less than 0.05), with elevated levels (twofold increase) of FSH in the combined severe oligospermia and azoospermia (P less than 0.01) groups. Moreover, augmented (P less than 0.01) bioactive FSH levels were also observed in this group of patients. The mean bioactive to immunoreactive FSH ratio was also negatively correlated with sperm counts (P less than 0.005). In addition, T/LH ratios were inversely correlated with immunoreactive (P less than 0.05) and bioactive (P less than 0.05) FSH, which may indicate that altered Leydig cell function is involved in the augmented secretion of FSH. The data presented in this study indicate that immunoreactive FSH, as measured in oligospermia and azoospermia, does not exhibit decreased bioactivity.