A comparison of serum free estriol with spontaneous urine total estrogen and estrogen/creatinine ratio

Abstract
A mathematical comparison was made between the serum free estriol levels, the urine total estrogen, and the total estrogen/creatinine ratio in 83 pregnant women during the last trimester of pregnancy. The blood serum and spontaneous urine samples were obtained simultaneously, and each woman was sampled once. The serum estriol was measured by radioimmunoassay and the urine estrogen levels measured by the aqueous fluorometric Kober technique. The group averages of the 3 different measurements paralleled each other throughout the 3rd trimester. Linear regression and correlation studies of the measured levels for each subject by the different methods were statistically significant (P .ltoreq. 0.0001). The correlation factor between serum free estriol and spontaneous urine total estrogen was +0.5991, and between serum free estriol and the spontaneous urine total estrogen/creatinine ratio was +0.8086. The very high correlation between the 2 urine and the serum methods suggest that spontaneous urine samples may be used to measure estrogen changes during pregnancy [for fetal distress].