Urinary excretion of oestriol and plasma levels of unconjugated and total oestriol during late uncomplicated pregnancy.

Plasma levels of unconjugated and total oestriol and urinary excretion of oestriol were measured in ten healthy women with uncomplicated pregnancy and with normal renal function. A significant correlation between plasma total oestriol and urinary oestriol was found in five out of ten patients and between plasma total and unconjugated oestriol in only four of ten patients. When the data from the ten patients were combined there were significant correlations between urinary oestriol and the two plasma oestriol species as well as between plasma unconjugated and total oestriol. The mean urinary oestriol excretion correlated significantly with the mean urine volume. No significant correlation was found in the individual subjects between oestriol clearance and creatinine clearance, but the combined data from the ten patients yielded a highly significant correlation. The differences within or between days was highest for plasma unconjugated oestriol and lowest for urinary oestriol/mmol of creatinine. Over a three to four day period, a drop of 20 per cent in urinary oestriol/mmol of creatinine, 25 per cent in urinary oestriol/24 hours, 35 percent in plasma total oestriol and 40 per cent in plasma unconjugated oestriol do not necessarily indicate fetal danger.