Evaluation of Vaginal Smear, Serum Gonadotropin, Protein-Bound Iodine, and Thyroxine-Binding as Measures of Placental Adequacy*

Abstract

During pregnancy the characteristic increase in the thyroxine-binding capacity of the circulating globulin, TBG (1-3), is associated with a retarded rate of thyroxine turnover (4) and an increase in the concentration of hormonal iodine (PBI) in the plasma (1-4). These alterations in iodine metabolism have not been found in women with choriocarcinomas who excrete large quantities of chorionic gonadotropin (5), but do occur in nonpregnant individuals given large quantities of estrogens (6-8). It has been concluded, therefore, that during pregnancy these phenomena result from systemic effects of placental estrogens. Moreover, the sera of aborting women often fail to show the characteristic increase in serum PBI (9) and in thyroxine-binding by TBG (2).In the past, attempts have been made to use the concentration of PBI as an indicator of fetal viability (9, 10); however, as appears to be true of studies of urinary or plasma chorionic gonadotropin determinations, pregnandiol and estrogen levels, and vaginal smears (11-15), the PBI has not proved satisfactory for routine use. It appeared possible, however, that assessment of TBG might prove of value as an indicator of placental function. For that reason a technique was developed for rapidly estimating serum thyroxinebinding, and its value in predicting the outcome *

Free thyroxine in human serum: simplified measurement with the aid of magnesium precipitation.

“…This is well illustrated in the euthyroid pregnant subjects with the characteristic elevation of PBI attributable to increased TBG concentration (1,(17)(18)(19)(20)(21)(22)(23)(24), but a low per cent free thyroxine, giving a computed free thyroxine iodine concentration in the low normal range. It is considered likely that the physiological activity of thyroxine depends upon the concentration of unbound hormone.…”

The Predictive Value of Thyroid “Test Profile” in Habitual Abortion

“…In an earlier paper we emphasized that a link exists between low globulin-bound iodine (the equivalent of the present TBG-held fraction), and the incidence of habitual abortion (Winikoff et al, 1960). Similarly Nicoloff et al (1962) found the TBG assay most valuable in predicting the outcome of pregnancy. Other authors maintain that a failure of thyroxine and/or TBG to rise from pregestational levels (no matter what they were) does not augur well for the outcome of pregnancy.…”

“…THERE have been many attempts to correlate an unsuccessful outcome of pregnancy with Five groups of patients were investigated: inadequate thyroid function (Man et al, 1951 ; Group 1.-70 normal pregnant women (con-Dowling et al, 1956;Winikoff et al, 1960; trols), Nicoloff et al, 1962 and1970;Magnin et al, Group 2.-36 pregnant women who carried a 1968; Jones and Man, 1969). A high proportion pregnancy to term but had a past of women with a low blood thyroxine level have history of two or more spontaneous either a premature delivery or a sFontaneous abortions, abortion (Jones and Man, 1969 were free from overt thyroid disease.…”

Thyroxine-Binding Globulin in Spontaneous Abortion

“…Generally, it has been claimed that inade quate thyroid function is combined with un successful outcome of pregnancy [1][2][3][4], Also, there exists a link between globulin-bound iodine (GBI) and the outcome of pregnancy, since low GBI has been claimed to be a warn ing of threatening abortion [3], Later on it has been reported that TBG is the most valuable variable as a predictor for the outcome of pregnancy and even so when compared to serum HCG in reflecting placental function [4], In that study an indirect method was used for estimating TBG. In the present study we used a direct method of measuring TBG.…”