THE PRECIPITABLE IODINE OF SERUM IN NORMAL PREGNANCY AND ITS RELATION TO ABORTIONS 1

Abstract

The serum precipitable iodine (SPI) has been detd. on one or more occasions during pregnancy in 46 women without complications or signs of overactivity or underactivity of the thyroid gland and with delivery at term. In only 3 instances was SPI observed below 6 [mu]g% after 16 weeks of pregnancy. In 9 patients with pregnancies complicated by conditions other than abnormal activity of the thyroid, SPI with one exception lay at the same high levels. This is also true of 14 patients still undelivered but with apparently normal pregnancies, well advanced. In those patients studies before and after pregnancy, SPI is found to rise early in pregnancy and to fall shortly after delivery. SPI has also been measured in a series of euthyroid pregnant women who aborted or who received thyroid substance to prevent abortion. There is some evidence that if SPI does not rise above about 6 [mu]g% during the first 16 weeks, pregnancy is unlikely to proceed to term, and that abortion is more common in those women whose SPI''s do not rise relatively early in pregnancy. Admn. of generous amts. of thyroid substance accelerates the rise of SPI. The. cases reported suggest that, if thyroid is given early enough it may diminish the tendency to abortion, but more controls are needed to establish these points. If thyroid is given to the pregnant woman, the SPI curve tends to follow a course similar to that of the untreated pregnant woman. The implications of this fact with respect to the nature and significance of the increment of SPI in pregnancy are discussed.