Screening in pregnancy with unconjugated serum estriol compared with urinary estriol

The diagnostic value of estriol determinations in high-risk pregnancies is frequently discussed in the literature. Estriol levels of urine and serum samples of 48 asymptomatic pregnant women were analyzed using direct radioimmunoassay. A correlation was found (r = 0.5997) between urine and serum samples, nevertheless the correlation was stronger (r = 0.8278) if 4 cases with extreme deviation were omitted. In these cases the serum estriol levels were high and the urine estriol levels were low. The outcome of the pregnancies was without any complication. Our observations suggest that determination of unconjugated serum estriol levels is more reliable in the monitoring of high-risk pregnancies, since they do not depend on renal and hepatic functions.