Abstract
Free [kestrone (E1) +estradiol (E2) in pregnant serum was measured by specific and sensitive E2 radioimmunoassay (RIA) system.
Serum was washed with petroleum ether and estrogen fraction was extracted by. ether. The extract was further washed with 3% sodium carbonate solution in order to remove estriol (E3) and then free (E1+E2) fraction was extracted by a mixture of petroleum ether: ether (2: 1).
The method of RIA was as follows: (1) 0.4ml of sample or standard E2,(2) 0.1ml (6m μCi) of 3H-E2 and (3) 0.1ml of anti E2-BSA-γ-gl, diluted to 1: 1600, were mixed and incubated. 3H-E2 bound to the antibody was precipitated at “one-half saturation” of a saturated ammonium sulfate solution and radioactivity of the precipitates was measured.
The range of measurement was 0.3-5.0ng/ml. Cross reaction of various steroids to E2 was 100% for E1, 4% for E3 and less than 0.03% for testosterone, hydrocortisone and progesterone. Coefficients of variations in the course of the repeated assays were 13.1-22.5% in early pregnancy, and the recovery rate was revealed to be 41.3±2.0 (S. D.).
Concentrations of free [E1+E2] of 69 cases of normal pregnant serum (9-42 weeks of pregnancy) showed a gradual increase according to the gestation periods. The mean values in the 4th, 7th and 10th months of pregnancy were 9.5, 16.6 and 29.5ng/ml, respectively. Blood samples were taken from 11 cases of normal puerperal women at various intervals after placental delivery and the serum levels of free [E1+E2] and HCG were measured. Their half-lives were 14.2 min and 3 hrs 42 min, respectively.
Estimation was made also on 29 cases of complicated pregnancy (hydatidiform mole, intrauterine fetal death, threatened abortion, anencephalus, twin, toxemia, overterm).
In conclusion, it may be safely said that the levels of serum free [E1+E2] are a more suitable index for placental function in the diagnosis or prognosis of threatened abortion due to hypofunction of placenta or determination of the timing of induction of delivery, since its half-life is extremely shorter than HCG.
