Short-term variations in urinary estriol and renal function. Possible effects of extraneous conditions.

Variation in urinary excretion of estriol was found to be related to physical activity and climate conditions. Estriol content of sweat was studied but was found not to be of an order to explain the variation observed. Estriol clearance rate was significantly reduced even by moderate physical activity. Creatinine clearance was not affected to the same extent. Different explanations to the findings are discussed. The need for strictly standardized conditions during urine sampling for estriol assays in risk pregnancies is stressed.