The Effects of Fasting on Serum and Urinary Gonadotropins in Obese Postmenopausal Women

Ten postmenopausal women, 12–27% over their ideal weight, fasted for 10 days for weight reduction. All lost at least 4.4% of their weight and demonstrated ketonemia, hyperuricemia (if not treated with Allopurinol), ketonuria, and natriuresis. Serum gonadotropin concentrations measured by RIA for 2 control, 10 fasting, and 2 refeeding days did not differ significantly [(LH, 12.1 ± 2.0 (mean ± SE) mlU/ml (LER 907); FSH, 47.6 ± 5.2 mlU/ml (LER 907)]. The mean urinary excretion of LH (measured by acetone precipitation and RIA) on the control days was 109.3 ± 14.5 (±SE) IU/24 h [Second International Reference Preparation of human menopausal gonadotropin (2nd IRP-hMG)], on fasting day 1 it was significantly higher (139.0 ± 30.3), and by day 8 it had reached 427.7 ± 88.5 (P < 0.0025). On refeeding day 2, a significant decrease in LH excretion occurred (LH, 188.1 ± 23.6 IU/24 h). Similar elevations in LH excretion during fasting were demonstrable when the urine was extracted with kaolin and the LH concentration w...