Relationship of testicular volume to semen profiles and serum hormone concentrations in infertile Japanese males

Objective-We studied the relationship between testicular volume and semen duality and also between testicular volume and seminiferous tubular or Leydig cell function in infertile Japanese males. Methods-The testicular Volumes of 486 infertile Japanese males were measured by an orchidometer. Semen samples were analyzed according to the guidelines of the World Health Organization. Serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone were measured by radioimmunoassay. The subjects were divided into 10 groups according to testicular volume, and the variables from each group were analyzed and compared. Results-Testicular volume had the strongest positive correlation with sperm density, followed in decreasing order by total sperm count per ejaculate, total motile sperm count per ejaculate, and percentage of motile sperm. Testicular volume had the strongest negative correlation with serum FSH concentrations, followed by serum LH concentrations. In contrast, no significant correlations were found between testicular volume and semen volume or serum testosterone concentrations. Multiple regression analysis of dependence of testicular volume on semen profiles and serum hormone concentrations revealed that the only significant factor was serum FSH concentration. Sperm density was under the limit of normal in patients with a testicular volume of less than 30 mt. In these patients, serum FSH concentrations were abnormally increased. Patients with a testicular volume of less than 10 mt were azoospermic, while volumes of less than 20 mt were associated with severe oligozoospermia. Conclusions-Testicular volume has a direct correlation with semen profiles, and the critical testicular volume indicating normal testicular function is approximately 30 mt. The measurement of testicular volume can be helpful for rapidly assessing fertility at the initial physical examination.