Influence of oral contraceptive agents on kidney function and protein metabolism

The present study was an investigation of the effect of oral contraceptives on kidney function as well as a brief examination of protein metabolism, since glomerular filtration rate depends to a large extent on daily protein intake. 28 healthy women not taking contraceptives and 46 healthy women (aged 20-28 y) on one of three different types of oral contraceptive (combination preparations) were investigated [Minulet/Femovan, Marvelon, Diane]. In all groups on oral contraceptives the endogenous creatinine clearance was significantly increased. The potassium excretion rate was significantly elevated in the groups taking Marvelon and Diane, and the sodium excretion rate was significantly increased in those on Minulet/Femovan and Diane. In all groups on contraceptives the albumin excretion rate was numerically but not significantly elevated. No significant differences were found in the daily oral protein intake or the nitrogen excretion rate on comparing the groups taking contraceptives with the control group. However, the ratio nitrogen excretion rate/daily protein intake was significantly increased in those on Minulet/Femovan and Diane. The study has shown that besides their various effects on renal tubular function, oral contraceptives are able to increase the glomerular filtration rate, and certain types have a protein catabolic effect.