Serum thyrotropin by ultrasensitive immunoradiometric assay and serum free thyroid hormones in pregnancy

1986 ◽  
Vol 9 (2) ◽  
pp. 185-189 ◽  
Author(s):  
A. Pacchiarotti ◽  
E. Martino ◽  
L. Bartalena ◽  
L. Buratti ◽  
C. Mammoli ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Immunoradiometric Assay ◽  
Serum Free ◽  
Free Thyroid Hormones ◽  
In Pregnancy

Serum free thyroid hormones in subclinical hypothyroidism

1986 ◽  
Vol 9 (4) ◽  
pp. 315-319 ◽  
Author(s):  
A. Pacchiarotti ◽  
Enio Martino ◽  
L. Bartalena ◽  
F. Aghini-Lombardi ◽  
L. Grasso ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Subclinical Hypothyroidism ◽  
Serum Free ◽  
Free Thyroid Hormones

Free thyroxin and free triiodothyronine as measured by equilibrium dialysis and analog radioimmunoassay in serum of patients taking phenytoin and carbamazepine.

1985 ◽  
Vol 31 (12) ◽  
pp. 1993-1996 ◽  
Author(s):  
K Liewendahl ◽  
S Tikanoja ◽  
T Helenius ◽  
H Majuri
Keyword(s):  
Thyroid Hormones ◽  
Plasma Proteins ◽  
Equilibrium Dialysis ◽  
Immunoradiometric Assay ◽  
Free Triiodothyronine ◽  
Free Thyroid Hormones ◽  
Incremental Effect ◽  
The Mean ◽  
Mean Concentration

Abstract We measured free thyroxin (FT4) and free triiodothyronine (FT3) in serum of patients taking the anti-epileptic drugs phenytoin and carbamazepine, both by equilibrium dialysis procedures and analog-type radioimmunoassays. By either assay, the mean concentration of FT4 was significantly decreased in patients receiving either drug, whereas their FT3 concentrations were normal or only slightly decreased. Adding therapeutic concentrations of these drugs in vitro to control sera had a small or no incremental effect on FT4 and FT3 as measured by either method, but adding greater concentrations of the drugs in vitro markedly increased the concentrations of the free hormones. These results indicate that the main mechanism of the decrease in concentrations of free thyroid hormones in serum during therapy with anticonvulsant drugs is not the displacement of hormones from their binding to plasma proteins. We also determined, using a new and sensitive immunoradiometric assay, that patients taking carbamazepine, but not those taking phenytoin, had significantly less thyrotropin in the serum.

Serum free thyroid hormones in different degrees of hypothyroidism and in euthyroid autoimmune thyroiditis

1987 ◽  
Vol 114 (4) ◽  
pp. 559-564 ◽  
Author(s):  
C. Ferrari ◽  
A. Paracchi ◽  
E. Parisio ◽  
F. Codecasa ◽  
M. Mucci ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Thyroid Function ◽  
Autoimmune Thyroiditis ◽  
Subclinical Hypothyroidism ◽  
Healthy Subjects ◽  
Direct Determination ◽  
Serum Free ◽  
Free Thyroid Hormones ◽  
Hypothyroid Patients

Abstract. Serum total and free T4 and T3, thyroxinebinding globulin (TBG) and TSH, basal and 20, 30 and 60 min after TRH (200 μg, iv), were evaluated in 125 hypothyroid patients (38 with severe, 23 with mild, and 64 with subclinical hypothyroidism), in 35 euthyroid subjects with autoimmune thyroiditis, and in 51 healthy controls. T4/TBG and T3/TBG ratios were also calculated. A significant decrease in all indices of thyroid function except for T3 occurred simultaneously with a significant increase in basal and TRH-stimulated TSH levels from healthy subjects to subclinical hypothyroids, from subclinical to mild and from mild to severe hypothyroids; euthyroid patients with autoimmune thyroiditis did not differ from healthy subjects. All severe hypothyroid patients had low T4 as well as free T4 (FT4), free T3 (FT3), T4/TBG and T3/TBG ratios, but among mild and subclinical hypothyroids direct determination of FT4 and FT3 proved to be a better index of thyroid function than determination of T4 and T3 even after correction for TBG levels. FT4 was the most commonly abnormal index (19 of 23 subjects with mild and 14 of 64 with subclinical disease). Regression analysis showed that FT4, T4/TBG ratio, T4, and FT3 had a significant inverse correlation with TSH in hypothyroid patients. Discriminant analysis showed that among the thyroid parameters, FT4 is the variable which discriminates best between control subjects and the 3 groups of hypothyroid patients. These data extend previous reports and in a large series of patients confirm the biological meaning and the clinical value of direct measurement of serum free thyroid hormones in hypothyroidism. Nevertheless, the finding that both FT4 and FT3 are in the normal range in some patients with mild and in most with subclinical hypothyroidism indicates that increased TSH secretion remains the most sensitive index of thyroid failure.

Unexpected Elevated Free Thyroid Hormones in Pregnancy

Thyroid ◽  
2016 ◽  
Vol 26 (11) ◽  
pp. 1640-1644 ◽  
Author(s):  
Claudia Teti ◽  
Elena Nazzari ◽  
Marina Raffaella Galletti ◽  
Mattia Grazia Mandolfino ◽  
Francesca Pupo ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Free Thyroid Hormones ◽  
In Pregnancy

The influence of free fatty acids on the free fraction of thyroid hormones in serum as estimated by ultrafiltration

1987 ◽  
Vol 116 (1) ◽  
pp. 102-107 ◽  
Author(s):  
C. Bregengåard ◽  
C. Kirkegaard ◽  
J. Faber ◽  
S. Poulsen ◽  
K. Siersbæk-Nielsen ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Thyroid Hormones ◽  
Healthy Subjects ◽  
Binding Proteins ◽  
Free Fraction ◽  
Nonthyroidal Illness ◽  
Serum Free ◽  
Free Thyroid Hormones ◽  
Serum Pool ◽  
Somatic Illness

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.

Serum free thyroid hormones in T3-toxicosis: a study of 35 patients

1983 ◽  
Vol 6 (1) ◽  
pp. 55-58 ◽  
Author(s):  
C. Ferrari ◽  
M. Romussi ◽  
P. Rampini ◽  
R. Benco ◽  
M. Boghen ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Serum Free ◽  
Free Thyroid Hormones

Transient Prealbumin- Associated Hyperthyroxinemia in TSH-Producing Pituitary Adenoma

1990 ◽  
Vol 29 (01) ◽  
pp. 40-43 ◽  
Author(s):  
W. Langsteger ◽  
P. Költringer ◽  
P. Wakonig ◽  
B. Eber ◽  
M. Mokry ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Case Report ◽  
Pituitary Adenoma ◽  
Thyroid Hormones ◽  
Protein Binding ◽  
Alpha Subunit ◽  
Normal Range ◽  
Thyroxine Binding Globulin ◽  
Free Thyroid Hormones ◽  
Transmission Computed Tomography

This case report describes a 38-year-old male who was hospitalized for further clarification of clinically mild hyperthyroidism. His increased total hormone levels, the elevated free thyroid hormones and the elevated basal TSH with blunted response to TRH strongly suggested a pituitary adenoma with inappropriate TSH incretion. Transmission computed tomography showed an intrasellar expansion, 16 mm in diameter. The neoplastic TSH production was confirmed by an elevated alpha-subunit and a raised molar alpha-sub/ATSH ratio. However, T4 distribution on prealbumin (PA, TTR), albumin (A) and thyroxine binding globulin (TBG) showed a clearly increased binding to PA (39%), indicating additional prealbumin-associated hyperthyroxinemia. The absolute values of PA, A and TBG were within the normal range. After removal of the TSH-producing adenoma, basal TSH, the free thyroid hormones and T4 binding to prealbumin returned to normal. Therefore, the prealbumin-associated hyperthyroxinemia had to be interpreted as a transitory phenomenon related to secondary hyperthyroidism (T4 shift from thyroxine binding globulin to prealbumin) rather than a genetically conditioned anomaly of protein binding.

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