Estriol and the Kidney in Pregnancy

Estriol-16α-glucosiduronate in the urine and serum of pregnant women was measured by a direct radioimmunoassay which was highly specific for this compound and did not require hydrolysis or chromatography. Urinary and serum estriol-16α-glucosiduronate increased as pregnancy progressed. Pregnant women with presumptive renal failure (toxemia of pregnancy, malignant hypertension, post renal transplantation, etc) showed low urinary levels of estriol-16α-glucosiduronate but normal serum levels. Their renal clearance of estriol-16α-glucosiduronate was calculated provisionally and compared to that of creatinine. The results suggest that some serum estriol is conjugated by the kidney and that the measurement of estriol-16α-glucosiduronate can be used as a clinical index of renal failure during pregnancy.