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  • Author: K. Siersbæk-Nielsen x
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C. Kirkegaard, Th. Friis and K. Siersbæk-Nielsen

ABSTRACT

A radioimmunoassay of serum T3 was developed displacing T3 from the thyroxine binding proteins by merthiolate. Separation of the free and the antibody bound fraction was accomplished by the use of dextran-coated charcoal. The addition of 14 mg BSA was shown to diminish the adsorption of the antibody bound fraction to charcoal.

In 90 controls serum T3 was 1.33 ± sd 0.29 ng/ml. None of 94 hyperthyroid patients had serum T3 values within normal range, whereas 12% of 34 hypothyroid patients had normal serum T3 values.

The T4:T3 ratio in serum was found to be 67.0 ± sd 11.9 in normals, while the ratio was significantly (P < 0.001) decreased as well in hyperthyroid as in hypothyroid patients.

The discriminant value of serum T3 was found to be superior to T4 in the diagnosis of hyperthyroidism, whereas serum T4 was found to be better with regard to hypothyroidism. However, correction of the influence of different TBG levels by calculating free T4 index and free T3 index showed that both parameters almost completely separated normals from patients with untreated hyperthyroidism, respectively hypothyroidism.

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K. Siersbæk-Nielsen and J. Mølholm Hansen

ABSTRACT

Repeated determinations of plasma T4, PBI, dialysable T4 and free T4 were undertaken on 31 mothers of full-term infants and ten mothers of premature infants in the perinatal period. The blood samples were obtained 2–7 hours before delivery, at delivery, 3–6 hours after delivery, 6–12 hours after delivery and on the 2nd, 3rd–4th and 5th–6th day after birth. Similar investigations were also undertaken on cord blood. A significant increase in the mean value for plasma T4 of approximately 25 % was found from before delivery to the time of delivery. This was followed by a rapid decrease, so that a return to values observed before delivery occurred on the 2nd day after delivery. Dial. T4 did not alter during the rapid variations in the plasma T4. Plasma T4 was found to be significantly increased in maternal blood at delivery as compared with cord blood but there was no significant difference in the mean values for free T4 in the cord blood and the maternal blood at delivery, suggesting a free passive passage of T4 via the placenta. The variations found have not been described previously and they provide a possible explanation for the disagreements between the results of previous investigators. The reason for the variations and their significance in assessing possible equilibrium between free T4 in the maternal blood and cord blood are discussed.

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K. Siersbæk-Nielsen and J. Mølholm Hansen

ABSTRACT

The binding capacity of thyroxine-binding globulin (TBG), and total and dialysable thyroxine in the cerebrospinal fluid (CSF) and in serum have been estimated in 13 euthyroid patients with normal and elevated CSF protein and in 5 hyperthyroid and 5 hypothyroid patients. In the normal group, the mean value of TBG in CSF was found to be 2.7 ng/ml and 207 ng/ml in serum. TBG in CSF in relation to the total protein content was found to be much higher than TBG in the serum in relation to the total serum protein. In the euthyroid patients with elevated CSF protein TBG was also increased but not proportional to the increase in the protein concentration. In the hyperthyroid patients TBG in CSF was decreased and was lower than the elevated total thyroxine values. Dialysable thyroxine, however, showed only a moderate increase indicating that proteins other than TBG must bind a considerable part of total thyroxine in CSF in hyperthyroid patients. In myxoedema TBG was found to be elevated in proportion to the slightly elevated CSF protein content. It is concluded that TBG in normal CSF seems to be the physiologically most important thyroxine-binding protein.

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J. Mølholm Hansen and K. Siersbæk-Nielsen

ABSTRACT

Four out of 19 patients treated with perphenazine who were investigated in 1962, and 5 out of 31 patients who were investigated in 1966 had a raised PBI. The increase was most marked in the patients investigated in 1962. Measurements of dialysable thyroxine revealed that the increase was not due to an increase in thyroxine-binding globulin. All 50 patients had normal serum thyroxine as estimated by Murphy's method. Most probably the increase in PBI was due to the fact that the perphenazine tablets contain an iodine compound, which in some subjects may become bound to the serum proteins.

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K. Siersbæk-Nielsen and J. Mølholm Hansen

ABSTRACT

Tyrosine and free thyroxine in the CSF and in serum has been measured in 24 euthyroid patients, in 11 patients with thyrotoxicosis and in 4 patients suffering from myxoedema. The thyrotoxic patients had elevated tyrosine levels in the CSF and in the serum, but rise in tyrosine was greater in the CSF than in the serum and the mean ratio CSF tyrosine/serum tyrosine was significantly elevated as compared to the euthyroid group. In the hypothyroid group, in spite of decreased serum tyrosine values the CSF tyrosine was not decreased. Free thyroxine in the CSF was elevated in the thyrotoxic patients and decreased in the hypothyroid patients. In euthyroid, hyperthyroid and hypothyroid patients an equilibrium was found between free thyroxine in the CSF and in the serum. No correlation was found within the groups between the individual values of tyrosine in the serum and in the CSF or between tyrosine and free thyroxine in the serum and in the CSF.

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E. Hansen, C. Kirkegaard, Th. Friis and K. Siersbæk-Nielsen

ABSTRACT

The response in serum thyrotrophin (TSH) to thyrotrophin releasing hormone (TRH) has been studied in 5 euthyroid patients with familial thyroxine-binding globulin (TBG) deficiency. Total serum thyroxine (T4), serum triiodothyronine (T3) and free T4 index and free T3 index were significantly and equally decreased, but in spite of these findings the serum TSH and the response to TRH was normal. The TRH test seems to be a better indicator of the euthyroid state in familial TBG deficiency than the measurement of free T4 and free T3 in serum.

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L. Skovsted, M. Kristensen, K. Siersbæk-Nielsen and J. Mølholm Hansen

ABSTRACT

Urinary hydroxyproline was measured before, during, and after intravenous calcium-infusion in 5 normal subjects and in 4 patients with parathyroid adenomata. The results show that primary hyperparathyroidism cannot be diagnosed by means of a calcium-infusion-hydroxyproline test.

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J. Mølholm Hansen, Lis Skovsted and K. Siersbæk-Nielsen

ABSTRACT

Absolute iodine uptake (AIU), serum thyroxine (T4), free T4 index and serum triiodothyronine (T3) were studied in 48 women and 63 men aged 20 to 90 years. AIU decreased with age in both sexes to values in the oldest age groups of about 60 % of the values in the youngest age groups. AIU values for females were about 75 % of the values for males. Free T4 index was found to be unaltered with increasing age but serum T3 decreased with age. These findings and the previous demonstrated decrease in T4 degradation rate seem consistent with the assumption that T4 and T3 production decreases with advancing age.

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K. Siersbæk-Nielsen, J. Mølholm Hansen and E. Hippe

ABSTRACT

Elevated thyroxine-binding globulin capacity in serum (TBG) was found in five members of a family. Two males and three females in three generations had elevated TBG, protein-bound iodine and serum thyroxine but decreased dialysable thyroxine. The patients were clinically euthyroid and calculations of free thyroxine in serum and 131I uptake in the thyroid gland showed normal values. These results support the assumption that TBG is genetically controlled. The mode of transmission was consistent with dominant inheritance but it is not possible to determine whether it is x-linked or autosomal.

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C. Bregengåard, C. Kirkegaard, J. Faber, S. Poulsen, K. Siersbæk-Nielsen and T. Friis

Abstract. Thyroid hormones are displaced from their binding proteins in serum during nonthyroidal somatic illness, and FFA have been claimed to contribute. It seems mandatory to evaluate this effect using techniques for the measurements of serum free thyroid hormones in which serum remains undiluted. We measured the effect of 7 common human FFA on the free fraction of T4, T3 and rT3 in serum from healthy subjects using an ultrafiltration technique by which serum is diluted only minimally. In addition we measured the effect of oleic acid on the free fractions of the iodothyronines in pooled serum from healthy subjects and in pooled serum from patients with nonthyroidal illness. All FFA tested were able to displace both T4, T3 and rT3, but to a varying degree, arachidonic and linoleic acid being the most potent ones. A 20% increase in the free fractions of T4, T3 and rT3, respectively, was obtained by adding between 1.7–3.3 mmol/l, 1.3–4.6 mmol/l and 1.0–2.4 mmol/l of the different FFA. A serum pool obtained from patients with nonthyroidal somatic illness was more sensitive to oleic acid than a serum pool obtained from healthy subjects, since 2–3 times less oleic acid was necessary to induce a 20% increase in the free fractions of thyroid hormones. It is concluded that FFA are able to displace both T4, T3 and rT3 from their serum binding proteins in healthy subjects as well as in patients with nonthyroidal illness. However, serum from patients with nonthyroidal illness was more sensitive to the displacing activity of oleic acid than serum from healthy subjects. This was possibly due to reduced affinity of the serum binding proteins to thyroid hormones, and it could be argued that a factor different from FFA seemed responsible.