In vitro radioassay techniques in the study of reproductive hormones

Testosterone (T) levels in the testicular tissue in varicocele were studied in relation to alterations of testicular function. Testicular T levels were measured by a modified radioimmunoassay procedure in which 3H-testosterone was used as a tracer to monitor losses during extraction of the hormone. Serum follicle stimulating hormone (FSH), luteinizing hormone (LH) and T levels were measured by conventional radioimmunoassay. Testicular function was evaluated from patient histories and physical examinations, and from the results of sperm counts and histological examinations of biopsy specimens. In 4 control patients mean testicular T was 520 +- 127 ng/g tissue and the mean ratio testicular T/serum T 104 +- 47. In the majority of 17 patients with unilateral varicocele, testicular T was within normal limits, but in 3 patients with severe testicular damage values of 2700, 2373 and 1437 ng/g were recorded. Serum T levels were normal in the majority of patients and decreased in 2. Serum FSH levels were normal in the majority of patients and increased in 3. Serum LH levels were increased in approximately one half of patients. The results are considered indicative of impaired Leydig cell function in varicocele. It appears, however, that decreased T production is compensated by increased LH production and that the germinal cells are not deprived of T