Increases in Serum Thyroxin during Uncomplicated Pregnancy.

Danowski, T. S.; Gow, R. C.; Mateer, F. M.; Everhart, W. C.; Johnston, S. Y.; Greenman, J

doi:10.3181/00379727-74-17892

Cited by 31 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The thyroid gland may become enlarged and hyperplastic (1,2), thyroidal uptake of radioiodine is increased (3,4), "conversion" of blood iodide to organic form is more rapid (4), and the serum proteinbound iodine (PBI) is elevated (5,6). Although these alterations are like those seen in hyperthyroidism, they appear to be associated, in early pregnancy at least, with an unequivocally euthyroid state.…”

mentioning

confidence: 87%

See 1 more Smart Citation

Thyroxine-Binding by Serum Protein in Pregnancy and in the Newborn

Robbins¹,

Nelson²

1958

J. Clin. Invest.

View full text Add to dashboard Cite

Thyroid structure and function in man undergo a number of changes during pregnancy. The thyroid gland may become enlarged and hyperplastic (1, 2), thyroidal uptake of radioiodine is increased (3, 4), "conversion" of blood iodide to organic form is more rapid (4), and the serum proteinbound iodine (PBI) is elevated (5, 6). Although these alterations are like those seen in hyperthyroidism, they appear to be associated, in early pregnancy at least, with an unequivocally euthyroid state. Whereas the PBI rises as early as the first or second month of gestation, and remains at about the same level throughout pregnancy, elevation of the basal metabolic rate (2, 7) begins in the latter half of pregnancy and rises progressively. Circulatory changes, such as increased cardiac output (8), may precede the rise in oxygen consumption but these also change progessively until shortly before term.It has been postulated that alterations in the interaction of thyroid hormone with serum proteins might provide an explanation for these paradoxical findings (6). Inasmuch as circulating thyroxine is largely bound to what appears to be a specific alpha globulin (TBP) (9, 10), attention has been directed toward this protein in pregnancy. It has been demonstrated that TBP in pregnancy has an increased ability to complex thyroxine (10-13).In the present study, the thyroxine-binding capacity of TBP has been quantitated during the course of normal pregnancy and in newborn infants. From these data it has been possible to calculate an approximate concentration of free thyroxine in the serum of these subjects. METHODSSerum was obtained from 16 women during and after uncomplicated pregnancies, usually after an overnight fast, from umbilical vein blood sampled at delivery in three subjects, and from external jugular venipuncture in two infants on the third day after delivery. Mixtures of serum with I13'-labeled L-thyroxine 1 were prepared according to the procedure described previously (14). Prior to use, each of the eight thyroxine preparations employed was tested for radiochemical purity by chromatography, and was repurified, when necessary, to a purity of 90 per cent or better by an extraction procedure (15). Iodine analyses2 were performed by a modification of the method of Zak, Willard, Myers, and Boyle (16). The thyroxine-serum mixtures were subjected to zone electrophoresis on filter paper strips, using barbital buffer, pH 8.6, ionic strength 0.1, and a "reverse-flow" technique (15). This modification of the electrophoresis procedure avoided the inclusion of albumin-bound thyroxine in the alpha globulin zone.For measurement of the thyroxine-binding capacity of TBP, the quantity of thyroxine added to each serum was sufficient to effectively saturate the thyroxine-binding sites on TBP. Actual saturation of these sites is approached asymptotically (15). Analysis of data obtained with normal sera (10), however, had indicated that the amount of thyroxine associated with alpha globulin reaches an effective plateau when less than 60 per cent of t...

show abstract

mentioning

confidence: 87%

“…It has been postulated that alterations in the interaction of thyroid hormone with serum proteins might provide an explanation for these paradoxical findings (6). Inasmuch as circulating thyroxine is largely bound to what appears to be a specific alpha globulin (TBP) (9,10), attention has been directed toward this protein in pregnancy.…”

mentioning

confidence: 99%

Thyroxine-Binding by Serum Protein in Pregnancy and in the Newborn

Robbins¹,

Nelson²

1958

J. Clin. Invest.

View full text Add to dashboard Cite

show abstract

“…In studies of medically treated hyperthyroid patients, however, a number of values for SPI proved unexpectedly high in comparison with other measures of thyroid activity (5,7). Danowski and associates (8)(9)(10) reported that SPI of normal individuals and pregnant women rose after the administration of potassium iodide. It had also been discovered that certain iodine-containing compounds commonly used for diagnostic and therapeutic purposes formed combinations with the proteins of the serum and therefore were measured with SPI (11).…”

mentioning

confidence: 99%

“…Taurog and Chaikoff (4) found that 73 to 93 per cent of the iodine of normal plasma behaved like thyroxine inasmuch as it remained in butanol extracts after these had been washed with Blau's reagent. Danowski and associates (8)(9)(10) compared the iodine extracted by butanol with SPI in the sera of normal individuals, pregnant women, and persons taking potassium iodide. The mean value for iodine extraced by butanol in the sera from 23 healthy males and nonpregnant females and 21 pregnant women amounted to 69 per cent of SPI (10).…”

mentioning

confidence: 99%

“…Danowski and associates (8)(9)(10) compared the iodine extracted by butanol with SPI in the sera of normal individuals, pregnant women, and persons taking potassium iodide. The mean value for iodine extraced by butanol in the sera from 23 healthy males and nonpregnant females and 21 pregnant women amounted to 69 per cent of SPI (10). In five normal persons the ratio, butanolextractable iodine (BEI): SPI varied from 0.65 to 0.82 (8).…”

mentioning

confidence: 99%

See 1 more Smart Citation