[Annual variations in plasma testosterone levels in prepuberal subjects].

40 prepubertal boys, aged 6 to 10 years, were studied from 1977 to 1979 in order to evidence any circannual rhythm in the testosterone plasmatic levels. The patients observed in the following life schedule: nocturnal rest from 2200 to 0600 circa, meals at 0800, 1300, 1900. Plasma samples were taken at 0800 and testosterone was assayed by RIA. Testosterone data were fitted a cosine function, by least square method in order to describe any rhythm and to estimate its parameters:mesor, amplitude, acrophase. A significative circannual rhythm in the testosterone levels is present (P= 0.008) with Acrophase in July (-198.38 degrees +/- 18.26 ES). Our study suggests that a significative testosterone rhythm, with circannual periodicity, is present also in prepubertal age.