Rapid Oscillations in Plasma Levels of Testosterone, Luteinizing Hormone, and Follicle-Stimulating Hormone in Men

Abstract

A study designed to define the oscillatory pattern of plasma levels of testosterone luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in 4 young adult men was carried out. Blood samples were obtained every 2 minutes for 8 hours from the 3 normal and 1 oligospermic subjects. In each subject a different pattern of changes in hormone levels was found. In Subject 1 the predominant pattern was a slow sinusoidal fluctuation in testosterone levels. In Subject 2 changes in LH levels were the predominant finding. Subject 3 showed irregularly occurring FSH peaks that exceeded the coefficients of variation and which could have been undetected if less frequent sampling had been employed. Subject 4 the oligospermic volunteer demonstrated marked fluctuations in both FSH and LH. His LH levels were the highest and his FSH levels showed a regular sinusoidal pattern with a periodicity of approximately 30 minutes. In all subjects rapid variations in plasma testosterone levels were noted. No correlation was apparent between the levels of the 3 hormones in any of the subjects. It is concluded that although the observations made in the study cast doubt on the present concepts of negative feedback control of the pituitary-testicular axis additional studies are necessary to establish the physiological significance of the rapid oscillations in levels of plasma testosterone LH and FSH.