Summary A characteristic thyroid test profile is observed in pregnancy; it consists of an elevated serum thyroxine (TJ), thyroxine binding globulin (TBG) and electro‐phoretic index (EI) with lowered triiodothyronine resin uptake (T3U), the free thyroxine index (FTI) remaining in the normal range. An investigation was made of progressive changes in these parameters in 70 normal pregnant women, 34 pregnant women with a past history of habitual abortion who carried to term, seven habitual aborters who miscarried again, and 49 women at the time of spontaneous miscarriage. The results indicated that normal women reached a typical pregnancy thyroid test profile at seven to eight weeks' gestation while habitual aborters carrying a pregnancy to term reached it at 14 to I5 weeks and almost all patients who miscarried never reached it at all. In addition, four women who had aborted previously and were treated with thyroxine throughout six pregnancies, developed a normal “thyroid profile” and carried their pregnancy to term. The significance of the “predictive value” of the test profile is discussed.
The fluorometric method of Weil-Malherbe and Bone was used to investigate plasma catecholamine levels in the neonatal period. Full-term normal infants were found to have plasma adrenaline levels of 0.35 ± 0.64 µg/l and noradrenaline levels of 2.39 ± 2.69 µg/l. Premature infants had plasma adrenaline levels of 0.86 ± 1.21 µg/l and noradrenaline levels of 3.24 ± 2.03 µg/l. Twelve premature infants with the respiratory distress syndrome showed a significant and fourfold increase in adrenaline concentration and a nonsignificant increase in the level of noradrenaline. In seven infants with placental insufficiency and postmaturity there was a significant and eightfold increase in adrenaline. The importance of these findings is discussed, particularly with respect to hypoxia.
1. The total serum thyroxine, tri-iodothyronine resin uptake, total plasma protein concentration and the free thyroxine index (FTI) were determined repeatedly, at 07.15, 13.00 and 22.30 hours over 4 days, in six healthy young men. 2. There was a significant diurnal variation in the total serum thyroxine concentration but this reflected changes in the binding capacity of serum proteins and in the total plasma protein concentration which could be explained by changes of posture. The FTI, and presumably therefore the free thyroxine concentration, varied very little with the time of day. 3. The FTI varied significantly from day to day in three of the six subjects, presumably as a result of changes in thyroxine secretion because the serum binding capacity did not vary. 4. The subjects' sleep at night was assessed by electro-encephalogram. In days when the FTI was highest for a particular subject his sleep was more fragmented by spontaneous awakenings, the amount of rapid-eye-movement sleep was reduced and that of delta-wave sleep was increased, implying that variations in thyroid function over a period of a few days in healthy subjects can be of physiological significance. The cause of these variations is uncertain.
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