A direct radioimmunoassay for estriol-16alpha-glucosiduronate: its use in the determination of plasma and urine levels and renal clearance of this conjugate in pregnancy

Hormonal monitoring of early pregnancy by a direct radioimmunoassay of steroid glucuronides in first morning urine

The usefulness of the direct 4-hour radioimmunoassay of estriol-16-glucuronide (E3G) and pregnanediol-3-glucuronide (P2G) in first morning urine (FMU) for establishing a prognosis of the early pregnancy outcome was evaluated in 106 patients that became pregnant. Microaliquots of FMU were serially assayed from day 3 of the conception cycle until day 80 of pregnancy. The E3G and P2G profiles of 19 pregnancies which terminated in spontaneous abortion with either a diagnosis of the blighted ovum syndrome (n = 11) or presumption of a corpus luteum/trophoblast failure (n = 8) have been compared with those of clinically normal pregnancies (n = 87). Normal pregnancies displayed typical patterns of E3G and P2G development, while variations were observed in abortive events that reflected changes of the fetoplacental unit.

Plasma estrogens in the assessment of fetoplacental function

A retrospective study has been undertaken to assess the diagnostic value of plasma estriol (E3) determinations, as compared with determinations of other biochemical parameters, in predicting the outcome of pregnancy. The normal levels of plasma unconjugated and total E3 were determined on weekly samples obtained during the third trimester of 258 normal pregnancies. Weekly concurrent specimens of plasma and 24-hour urine collections were obtained from 17 high-risk pregnancies associated with hypertension, intrauterine growth retardation and diabetes. Determination of plasma unconjugated and total E3 were made along with human placental lactogen (HPL), urinary E3, and other biophysical parameters such as the oxytocin challenge test, non-stressed test, ultrasonography, etc. The results of plasma E3 were not reported nor used for the clinical management of the patient. The data suggests that weekly plasma determinations were of little value in the assessment of feto-placental status. Some observations on the extent of variability of plasma E3 are discussed.

An assay for urinary estriol-16 alpha-glucuronide based on antibody-enhanced chemiluminescence

An immunoassay for estriol-16 alpha-glucuronide in pregnancy urine is described that utilizes antibody-enhanced chemiluminescence. The steroid glucuronide was covalently conjugated with the chemiluminescent marker aminobutyl-ethyl-isoluminol. The light yield of this conjugate upon oxidation was augmented by specific antibody, and this effect was inhibited by addition of the homologous steroid glucuronide (10-100 pg) in a dose-dependent manner. The assay does not require separation of bound and free ligand and proved satisfactory with respect to sensitivity, precision and accuracy. Assay results obtained by radioimmunoassay and chemiluminescence immunoassay were in good agreement (r = 0.98; n = 25).