[Effect of sex on annual variations in GH response to insulin hypoglycemia in prepuberal subjects of small stature].

86 males and 66 females, aged 6 to 10 years, affected by short stature (SDs -2 according to Tanner), were investigated from 1977 to 1979 in order to evidence any circannual rhythm in the GH response to insulin test. The patients were hospitalized one week before the study starting and they observed the following life schedule:nocturnal rest from 2200 to 0600, meals at 0800, 1300, 1800. The insulin test (0,1 UI/Kg body weight) were administered at 0800. Plasma samples were taken before and after 20, 40, 60, 90 minutes. The single basal data and the peak were fitted a cosine function by least square method in order to describe amy rhythm and to estimate its parameters:mesor, amplitude, acrophase. A significative circannual rhythm in the GH response to insulin is present in the female subjects, with acrophase in December (-354.85 degrees +/- 21.93). Our study suggest that the sex may influence the circannual response of GH to insulin stimulus from prepubertal age.