A New Theoretical Description of the Binding of Thyroid Hormones by Serum Proteins

Princé, H. P.; Ramsden, D.

doi:10.1111/j.1365-2265.1977.tb01330.x

Cited by 47 publications

(12 citation statements)

References 22 publications

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“…The mean concentration of normal u-TBG obtained thus was 15.4 mg/l or 257 nmol/l, assuming a TBG molecular weight of 60 000 daltons (Marshall & Pensky, 1971). This is more than twice the value of 95.8 nmolil calculated by Prince & Ramsden (1977). One of the reasons for this discrepancy may be the difference in the TBG concentration; the TBG level in their measurements is half of that in our study.…”

Section: Discussioncontrasting

confidence: 86%

Serum Concentration of Unsaturated Thyroxine‐binding Globulin in Hyper‐ and Hypothyroidism

Konno

Kakinoki

Miura

et al. 1985

Clinical Endocrinology

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The concentration of serum thyroxine (T4)-binding globulin (TBG) not binding T4 (unsaturated TBG, u-TBG) was determined in hyper- and hypothyroidism. u-TBG was expressed as the product of TBG concentration and the ratio of free TBG capacity to maximal TBG capacity as determined by reverse-flow electrophoresis. u-TBG concentration in normal sera (n = 40) was 15.5 +/- 2.3 mg/l (mean +/- SD), or 257 +/- 38 nmol/l for a molecular weight of TBG of 60 000 daltons. u-TBG levels were significantly lower in hyperthyroidism (7.1 +/- 2.3 mg/l, n = 16, P less than 0.001) and higher in hypothyroidism (21.7 +/- 5.0 mg/l, n = 22, P less than 0.001). Based on partial correlation analysis, u-TBG was inversely correlated to serum T4 (r = -0.586, P less than 0.001), but not correlated to triiodothyronine (T3) (r=-0.180, NS). There was a reciprocal correlation between u-TBG concentration and the T3 uptake value (r = 0.748, P less than 0.001). There was also a reciprocal correlation of u-TBG with both % free T4 (r = 0.425, P less than 0.001) and % free T3 (r = 0.377, P less than 0.001), when the data were subjected to partial correlation analysis. These results provide the values for u-TBG concentration in hyper- and hypothyroidism, and support the concept that the free fractions of serum thyroid hormones may be determined by the number of binding sites of the TBG molecule that are not saturated with T4 in hyper-and hypothyroidism.

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Section: Discussioncontrasting

confidence: 86%

Serum Concentration of Unsaturated Thyroxine‐binding Globulin in Hyper‐ and Hypothyroidism

Konno

Kakinoki

Miura

et al. 1985

Clinical Endocrinology

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“…TBG possesses binding sites of much higher affinity for T, and T3 than those of TBPA and Alb (22), and the increased serum TBG level determines the serum thyroid hormone concentrations in newborns (14). In attempting to evaluate the saturation of TBG binding sites, the individual ratios between serum concentrations of thyroid hormones and TBG were calculated.…”

Section: Nsmentioning

confidence: 99%

Serum Concentrations of Thyrotropin, Thyroid Hormones and Thyroid Hormone Binding Proteins During Acute and Recovery Stages of Idiopathic Respiratory Distress Syndrome

1979

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A total number of 27 premature infants with idiopathic respiratory distress syndrome (IRDS) and 52 healthy controls with comparable gestational age and body weights were studied during the first month of life. In infants with IRDS a reduced thyrotropin (TSH) response to birth was suggested, as serum TSH was lower in IRDS patients than in controls during the first two days of life. Low serum concentrations of thyroid hormones were found in the acute stage of IRDS reaching minimal values by day 3--5. After that period an increase in thyroid hormone levels occurred. The serum T2 increased to the level of healthy prematures by day 6--10, whereas the serum T4 increased to normal levels by day 21--30. Serum concentrations of thyroxine-binding globulin (TBG) were significantly lower in IRDS patients than in healthy controls; a gradual increase to normal levels occurred during recovery. Serum prealbumin (TBPA) levels in IRDS infants increased rapidly after birth and exceeded levels of healthy infants. Serum albumin values were not significantly different in the two groups of infants. The serum T4/TBG ratios were low during recovery from IRDS.

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“…More recently, Bannai et al (1985) have shown slight suppression of TBG levels in severely thyrotoxic patients, although mildly thyrotoxic individuals did not differ significantly from their normal controls. In this study, since serum TBG levels were actually at the upper end of the normal range, the most likely explanation for a discrepancy between total and free T4 levels is diminished affinity of TBG (Prince & Ramsden, 1977;Yoshida et al, 1981) and TBPA (Ingbar et al, 1965;Oppenheimer et al, 1963) for T4.…”

Section: Discussionmentioning

confidence: 55%

Low Serum TSH With Normal Total Thyroid Hormone Levels: An Indicator of Free T4 Excess

O'Malley

Rosenthal

Exley

et al. 1989

Clinical Endocrinology

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We have studied 18 patients with low serum thyrotrophin (TSH) levels accompanied by normal thyroxine (T4) and triiodothyronine (T3) levels in order to clarify whether or not they are thyrotoxic. Serum T4, T3, free T3, free T4 and TSH were estimated three times weekly for 3-4 weeks. Thyroxine binding globulin (TBG) levels were estimated on one occasion only. Thyroid hormone data were expressed as the cumulative probability of having at least one result above the relevant normal range by the nth sample (Pn). For free T4 this probability was 61% by the 10th sample. Free T4 values were confined to the upper half of the normal range or above throughout the study. In contrast, free T3 values were distributed evenly within the normal range (P10 = 12%). For total T4 and total T3, P10 was 34 and 11% respectively. Thus, subjects with subnormal TSH levels but normal T4 and T3 levels have been shown to have elevated serum free T4 levels, an indicator of biochemical hyperthyroidism.

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A New Theoretical Description of the Binding of Thyroid Hormones by Serum Proteins

Cited by 47 publications

References 22 publications

Serum Concentration of Unsaturated Thyroxine‐binding Globulin in Hyper‐ and Hypothyroidism

Serum Concentration of Unsaturated Thyroxine‐binding Globulin in Hyper‐ and Hypothyroidism

Serum Concentrations of Thyrotropin, Thyroid Hormones and Thyroid Hormone Binding Proteins During Acute and Recovery Stages of Idiopathic Respiratory Distress Syndrome

Low Serum TSH With Normal Total Thyroid Hormone Levels: An Indicator of Free T4 Excess

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