Butanol-Extractable Iodine of Serum 1

Man, Evelyn B.; Kydd, David M.; Peters, John P.

doi:10.1172/jci102469

Cited by 129 publications

(36 citation statements)

References 19 publications

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“…Some investigators have found higher mean Plil and bulanol-extracted iodine values in maternal blood at delivery than in cord blood [3, fi, 10, 18]. while others have found no dilference [2,9,17,22,23,25]. We have shown that maternal blood thyroxine levels are slightly, but significantly, higher than those in cord samples.…”

Section: Discussionmentioning

confidence: 39%

Thyroid Function Studied in Paired Maternal-Cord Sera and Sequential Observations of Thyrotropic Hormone Release during the First 72 Hours of Life

et al. 1971

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ExtractPituitary thyrotropic hormone (TSH) was measured in seven normal newborns followed during the first 72 hr of life. These infants demonstrated an acute unsustained release of TSH in the early minutes of postnatal life. Peak levels occurred between 15 and 150 min after birth, increasing from cord levels ranging from. 3.2 10.7 //units ml to a maximal elevation in sera of 25-l(>3 //units ml. This rise was followed by a steep decline in serum levels at an initial rate comparable to that reported for the half-life of the hormone. A slower rate of decay was noted after 120 min.The TSH levels in 20 normal paired maternal and cord samples indicated that cord levels were consistently higher (/ = 5.90, P < 0.001 ). Maternal levels were comparable to those found in nonpregnant adult females; however, cord levels of TSH were higher than that expected for normal children. Specificity of the TSH assay would indicate that immunoreactive TSH in maternal and cord sera was of pituitary origin.Maternal thyroxine levels were significantly greater than those of cord sera (/ = 3.31, P < 0.01), reflecting similarly higher levels of thyroxine-binding globulin (TBG) in maternal specimens (/ = 7.31, P < 0.001). No significant differences (/ = 1.11, P > 0.2) existed when levels of free thyroxine (FT.) in maternal and cord sera were compared. SpeculationThe relatively high levels of TSH in cord serum in the presence of normal or high normal free tliyroxine concentrations would suggest that the hypothalamic-pituitary responsiveness to thyroxine in the fetus is altered. Free thyroxine concentrations that maintain TSH in the euthyroid range in normal children are apparently unable to do so in the fetus. Any other hypothesis for this observation must necessarily postulate a persistent stimulus to TSH secretion in utero. One such postulated stimulus could be a relatively low serum concentration of free triiodothyronine (T ;) ) in the fetus.

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Section: Discussionmentioning

confidence: 39%

Thyroid Function Studied in Paired Maternal-Cord Sera and Sequential Observations of Thyrotropic Hormone Release during the First 72 Hours of Life

et al. 1971

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“…The values observed were higher than their accepted standard values for adult euthyroid subjects. Man et al [13] and Pickering et al [16], who measured thyroxine-like butanol-extractable iodine (BEI), demonstrated that the levels of BEI are similar in maternal and cord sera, but that a sharp increase occurs during the 1st week of life which reaches a peak by the 5th day with a return to values similar to those found in cord blood by the 18-20th day of life. Our findings of similar TT 4 levels in cord and maternal sera with a rise in the circulating levels of TT 4 by 1 week of age and a return to levels equal to those found in the cord blood by 1 month of age are in accordance with the previous data for PBI and BEI in the neonatal period.…”

Section: Discussionmentioning

confidence: 99%

“…During the first few days of postnatal life serum hormonal iodine values have been shown to increase significantly [4,9,10,13,14,16]. Absence of clinical signs of hyperthyroidism in the presence of laboratory findings suggestive of thyroid hyperactivity continues to be unexplained.…”

Section: Introductionmentioning

confidence: 99%

Serum Triiodothyronine, Total Thyroxine, and Thyroxine to Triiodothyronine Ratios in Paired Maternal-Cord Sera and at One Week and One Month of Age

et al. 1973

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ExtractTwenty-seven paired maternal-cord sera were analyzed for serum triiodothyronine (T3), total serum thyroxine (TT4), and maximum thyroxine globulin binding capacity (TBG cap.). In 17 of the infants the same studies were repeated at 1 week of age and in 10 of the 17 at 1 month. The mean T 3 value for the cord sera was 73.1 ± 20.4 ng/100 ml while the mean value for the maternal sera was 204 ± 49.2. The difference in the mean values was highly significant (P < 0.001). The maternal T 3 values are comparable with those of nonpregnant control subjects; those of cord blood fall below normal values. No statistically significant difference was found between the TT4 and TBG cap. values for cord and maternal sera. Both values were higher than the normal nonpregnant control values. At 1 week of age the serum T 3 levels had increased to a mean of 208.4 ± 40.9 ng/100 ml. This mean is significantly different from the one observed in cord sera (P < 0.001). A significant increase in the TT 4 values, mean 12.53 ± 2.2 Mg/100 ml (P < 0.01), was observed by the end of the 1st week. TBG cap. did not change significantly between birth and 1 week of age; by the end of the 1st month of life the serum TT 4 had decreased significantly to a mean of 9.5 ± 2.7 Mg/100 ml (P < 0.05), while the serum T 3 was maintained at a mean level of 228.2 ± 16.9 ng/100 ml, a value not significantly different from the one observed at 1 week of age. SpeculationThe extremely low levels of T 3 in the cord blood in the presence of TT 4 and TBG cap. values equal to those of the maternal blood suggest minimal materno-fetal placental transfer of T 3 . We have postulated that the low fetal T3 is responsible for the high levels of pituitary thyrotropic hormone (TSH) present in cord blood and early in the postnatal period and that the high levels of TT 4 with normal T 3 levels observed by the end of the 1 st week of life indicate defective peripheral deiodination of thyroxine (T 4 ) to T 3 and account for the lack of signs and symptoms of hyperthyroidism. By the end of 1 month of age TT 4 and T 3 values are within normal ranges, which indicates maturation in the metabolic pathway of T 4 and T 3 . 706T 3 , TT4, and T4/T3 in maternal-cord sera 707

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“…In all subjects two or more plasma protein bound iodine (PBI) or butanol extractable iodine (BEI) determinations were carried out1 (4,5). The BEI was done to avoid interference from previously administered inorganic iodine.…”

Section: Methodsmentioning

confidence: 99%

Radiothyroxine Turnover Studies in Thyroid Disease After Therapy

Sterling¹

1958

J. Clin. Invest.

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Butanol-Extractable Iodine of Serum 1

Cited by 129 publications

References 19 publications

Thyroid Function Studied in Paired Maternal-Cord Sera and Sequential Observations of Thyrotropic Hormone Release during the First 72 Hours of Life

Thyroid Function Studied in Paired Maternal-Cord Sera and Sequential Observations of Thyrotropic Hormone Release during the First 72 Hours of Life

Serum Triiodothyronine, Total Thyroxine, and Thyroxine to Triiodothyronine Ratios in Paired Maternal-Cord Sera and at One Week and One Month of Age

Radiothyroxine Turnover Studies in Thyroid Disease After Therapy

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