triiodothyronine--reverse and Abortion--Spontaneous

Concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine (rT3) in the placenta were measured in 7 patients with abortion, in 9 patients with premature delivery, in 16 normal pregnancies and in 4 pregnant women with Graves' disease. The placentas, obtained at delivery, were homogenized and centrifuged at 800 X g. T4, T3 and rT3 concentrations in the supernatants were extracted with 3 vol. of 99% ethanol and measured by RIAs. In normal pregnancy, placental T4, T3 and rT3 concentrations were 18.8 +/- 5.9 (mean +/- SD), 0.026 +/- 0.012, and 1.70 +/- 0.49 ng/g tissue, respectively. Ratios of rT3/T3 and rT3/T4 in the placenta were about 12 and 2.3 times as high as those in the fetal sera, respectively. There was a significant positive correlation between the placental T4 and the maternal or cord serum T4 concentrations. However, no correlation was found between the placental T3 or rT3 concentrations and the maternal or cord T3 or rT3 concentrations. In 4 patients with Graves' disease, the placental T4 concentration was elevated. These results indicate that the placental T4 concentration is influenced by both the maternal and fetal serum T4, and elevated ratios of rT3/T3 and rT3/T4 in the placenta might be due to the active placental 5-monodeiodination.

Topics: Abortion, Spontaneous; Female; Fetal Blood; Graves Disease; Humans; Obstetric Labor, Premature; Placenta; Pregnancy; Pregnancy Complications; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Production of rT3 from T4 in the placenta were measured in four patients with induced abortion, in three patients with spontaneous abortion, in 19 patients with various complications of pregnancy including Graves' disease, and in 18 normal pregnancies. The placentas, obtained at delivery, were homogenized and centrifuged at 800 X g. Supernatants (1 mg protein) were incubated with 1 microgram of stable T4 and 50 mmol/L dithiothreitol at 37 degrees C for 60 minutes. The generated rT3 was measured by radioimmunoassay (RIA). In patients who delivered at 38 to 41 weeks with complicated pregnancy, the net placental rT3 production from T4 was 7.3 +/- 2.5 ng/tube, which was not significantly different from that obtained in normal pregnancy (8.5 +/- 2.4) at an equivalent gestational age. In patients with abortions, the net placental rT3 generation from T4 was very high, and there was a significant negative correlation between the net placental rT3 production from T4 and gestational age. These results indicate that the net placental rT3 production from T4 is not affected by complications of pregnancy, but shows a significant change with the progress of gestation.

Topics: Abortion, Induced; Abortion, Spontaneous; Amniotic Fluid; Female; Fetal Blood; Gestational Age; Humans; Infant, Newborn; Iodide Peroxidase; Placenta; Pregnancy; Pregnancy Complications; Triiodothyronine, Reverse

The effect of abortion on serum concentration of thyroid hormones was studied in 11 normal women. After abortion, serum free and total T3 fall significantly, while free and total reverse T3, T4, TSH and TBG in serum show no significant variation. These data suggest that surgical stress in normal subjects may only influence 5'-deiodinase activity, and that the peripheral conversion of T4 to active T3 and inactive rT3 are controlled by different mechanisms.

Topics: Abortion, Spontaneous; Adult; Female; Humans; Pregnancy; Reference Values; Thyrotropin; Thyroxine; Thyroxine-Binding Proteins; Time Factors; Triiodothyronine; Triiodothyronine, Reverse