ABSTRACT
The effect of delivery on the serum concentration of thyroid hormones was studied in 25 euthyroid women. After delivery serum free and total T3 and T4 fell transiently with a simultaneous increase in reverse T3 while serum TSH and thyroxine binding globulin (TBG) concentrations showed no significant variation. These data suggest that i) similar to what happens in other stressful situations, delivery influences peripheral T4 metabolism, and ii) an elevation of TBG in serum in the early puerperium does not prevent these changes.
Subject(s)
Labor, Obstetric , Postpartum Period , Thyroid Hormones/blood , Thyroxine-Binding Proteins/metabolism , Adult , Female , Humans , Pregnancy , Thyrotropin/blood , Thyroxine/blood , Triiodothyronine/bloodABSTRACT
Conversion of thyroxine (T4) to 3,5,3'-triiodothyronine (T3) and reverse 3,3',5'-triiodothyronine (rT3) was measured in vitro in human placenta and fetal membranes. T4 (5 micrograms/ml) was incubated in 0.15 mol/l phosphate buffer with tissue homogenates for 2 h at 37 degrees C, and the T3 and rT3 generated were determined in ethanol extract using RIA methods. The placenta and chorion homogenates converted more T4 to T3 than to rT3; the placenta was more active than the chorion. In both tissues the highest converting activity was found in microsomal fractions.
Subject(s)
Extraembryonic Membranes/metabolism , Placenta/metabolism , Thyroxine/metabolism , Triiodothyronine, Reverse/biosynthesis , Triiodothyronine/biosynthesis , Chorion/metabolism , Female , Humans , Microsomes/metabolism , PregnancySubject(s)
Hypothyroidism/diagnosis , Thyrotropin/blood , Adolescent , Adult , Aged , Female , Humans , Hypothyroidism/blood , Male , Middle Aged , Radioimmunoassay , Thyrotropin-Releasing HormoneABSTRACT
In 14 hyperthyroid patient serum T4:rT3 ratio was significantly lower (399 +/- 20) than in the control subjects (572 +/- 20; p less than 0.001). A similar pattern was found for serum T3:rT3 ratio. In the hyperthyroid group the ratio was significantly lower (10.5 +/- 0.5) than in the control group (12.5 +/- 0.6; p less than 0.05). The data suggest that in hyperthyroidism the organism might shift conversion of T4 from biologically active T3 to poorly calorigenic rT3. It seems possible that the proportionately increased generation of rT3 than that of T3 may be a defence mechanism of the body, as it was found in systemic illnesses and starvation.
Subject(s)
Hyperthyroidism/blood , Triiodothyronine/blood , Adult , Aged , Female , Humans , Isomerism , Male , Middle Aged , Thyroxine/bloodABSTRACT
In 17 hypothyroid patients serum T3: rT3 ratio was 7.5 /+- 1.1 which was significantly lower than in control subjects (12.2 /+- 0.6; p less than 0.001). The data suggest that in hypothyroidism the organism might shift conversion of T4 from biologically active T3 to biologically inactive rT3 which may not be a defense mechanism of the body, as it was found in chronic systemic illness.
