LEVELS OF TESTOSTERONE AND LUTEINIZING HORMONE IN PLASMA SAMPLES TAKEN AT 10-MINUTE INTERVALS IN NORMAL MEN

Abstract

Recent studies of the circadian rhythm of steroidal and gonadotrophic hormones (Hellman, Nakada, Curti, Weitzman, Kream, Roffwarg, Ellman, Fukushima & Gallagher, 1970; Katongole, Naftolin & Short, 1971; Sederberg, Binder & Kehlet, 1971; Naftolin, Yen & Tsai, 1972) have shown that it is far from being the smooth diurnal variation usually reported. Instead rapid fluctuations in the levels of the hormones occur throughout the day. The present study was undertaken to confirm the findings of Naftolin et al. (1972) regarding luteinizing hormone (LH) and to attempt to correlate the plasma levels of LH with changes in plasma testosterone. Blood samples (5 ml) were obtained at 10-min intervals over an 8-h period, between 09.00 and 17.00 h, from three normal men. The men (aged 25–30 years) were recumbent throughout the experiment, except when urinating, and were awake and allowed to read or converse. Frequent sampling was facilitated by the use of an