scholarly journals Serum Free Thyroxine and Free Tri-Iodothyronine in Normal Children

1988 ◽  
Vol 25 (5) ◽  
pp. 536-539 ◽  
Author(s):  
J Butler ◽  
P Moore ◽  
G Mieli-Vergani ◽  
C Moniz
Keyword(s):  
Thyroid Hormone ◽  
Reference Range ◽  
Free Thyroxine ◽  
Normal Children ◽  
Serum Free ◽  
Upper Limit ◽  
Free Thyroid Hormone ◽  
The Mean ◽  
Mean Concentration ◽  
Serum Free Thyroxine

Serum free thyroxine (fT4) and free tri-iodothyronine (fT3) were measured in 138 normal school children, adolescents and their younger siblings, whose ages ranged from 3 months to 18 years. Mean fT4 concentration (16·8 pmol/L) was similar to the adult mean concentration of 17 pmol/L and all the values were within the adult reference range. At all ages the fT3 range was considerably higher than the adult reference range and the overall mean fT3 concentration (8·3 pmol/L) was at the upper limit of normal in adults. In subjects aged 13–18 years the mean fT4 concentration was higher and the mean fT3 concentration lower than in children aged 0–12 years. The reasons for these differences are not known, but the data obtained provide a useful guide to the interpretation of serum free thyroid hormone measurements in children.

SERUM FREE THYROXINE CONCENTRATION AND FREE THYROID HORMONE INDICES IN NORMAL PREGNANCY

1983 ◽  
Vol 18 (4) ◽  
pp. 431-437 ◽  
Author(s):  
M. R. HOPTON ◽  
K. ASHWELL ◽  
I. V. SCOTT and ◽  
J. S. HARROP
Keyword(s):  
Thyroid Hormone ◽  
Normal Pregnancy ◽  
Free Thyroxine ◽  
Serum Free ◽  
Free Thyroid Hormone ◽  
Serum Free Thyroxine

scholarly journals Misleading results from immunoassays of serum free thyroxine in the presence of rheumatoid factor

1997 ◽  
Vol 43 (6) ◽  
pp. 957-962 ◽  
Author(s):  
Anthony G W Norden ◽  
Rodwin A Jackson ◽  
Lorraine E Norden ◽  
A Jane Griffin ◽  
Margaret A Barnes ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Rheumatoid Factor ◽  
Equilibrium Dialysis ◽  
Thyroid Stimulating Hormone ◽  
Normal Serum ◽  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Serum Free Thyroxine ◽  
Stimulating Hormone

Abstract A novel interference with measurements of serum free thyroxine (FT4) caused by rheumatoid factor (RhF) is described. We found misleading, sometimes gross, increases of FT4 results in 5 clinically euthyroid elderly female patients with high RhF concentrations. All 5 patients had high FT4 on Abbott AxSYM® or IMx® analyzers. “NETRIA” immunoassays gave misleading results in 4 of the 5 patients; Amerlex-MAB® in 2 of 4 patients; AutoDELFIA®in 2 of the 5; and Corning ACS-180® and Bayer Diagnostics Immuno 1® in 1 of the 5. BM-ES700® system results for FT4 in these women remained within the reference range. Results for serum T4, thyroid-stimulating hormone, free triiodothyronine, thyroid-hormone-binding globulin, and FT4 measured by equilibrium dialysis were normal in all 5 patients. Drugs, albumin-binding variants, and anti-thyroid-hormone antibodies were excluded as interferences. Addition to normal serum of the RhF isolated from each of the 5 patients increased the apparent FT4 (Abbott AxSYM). Screening of 83 unselected patients demonstrated a highly significant positive correlation between FT4 (Abbott AxSYM) and RhF concentrations. Discrepant, apparently increased FT4 with a normal result for thyroid-stimulating hormone should lead to measurement of the patient’s RhF concentration.

Variations in Serum Free Thyroxine Concentration Within the Reference Range Predicts the Incidence of Metabolic Syndrome in Non-Obese Adults: A Cohort Study

Thyroid ◽  
2017 ◽  
Vol 27 (7) ◽  
pp. 886-893 ◽  
Author(s):  
Ladan Mehran ◽  
Atieh Amouzegar ◽  
Mahmood Bakhtiyari ◽  
Mohammad Ali Mansournia ◽  
Parnian Kheirkhah Rahimabad ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Cohort Study ◽  
Reference Range ◽  
Free Thyroxine ◽  
Obese Adults ◽  
Serum Free ◽  
Serum Free Thyroxine

Effects of Age and Health on the Euthyroid Reference Ranges for Serum Free Thyroxine and Free Triiodothyronine

1985 ◽  
Vol 24 (02) ◽  
pp. 57-65 ◽  
Author(s):  
J. E. M. Midgley ◽  
K. R. Gruner
Keyword(s):  
Lower Limit ◽  
Healthy Subjects ◽  
Thyroid Dysfunction ◽  
Reference Range ◽  
Free Thyroxine ◽  
Reference Ranges ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Young Subjects ◽  
Age Range

SummaryAge-related trends in serum free thyroxine (FT4) and free triiodothyronine (FT3) concentrations were measured in 7248 euthyroid subjects (age-range 3 months to 106 years). 5700 were patients referred to hospitals for investigation of suspected thyroid dysfunction, but who were diagnosed euthyroid. 1548 were healthy blood donors (age-range 18-63 years) with no indication of thyroid dysfunction. FT4 concentrations were little affected by the age, the sex or the state of health of the subjects in either group. Serum FT3 concentrations were significantly affected by both age and health factors. The upper limit of the euthyroid reference range for young subjects up to 15 years was about 20% higher (10.4 pmol/1) than for adult subjects older than 25 years (8.8 pmol/1). The change in the upper limits typical of young subjects to that typical of adults occurred steadily over the decade 15–25 years. After this age, little further change occurred, especially in healthy subjects. Additionally, the lower limit of the euthyroid range for FT3 was extended by the inclusion in the reference group of patients referred to hospitals. Compared with the lower limit of the FT3 range for healthy subjects (5 pmol/1), the corresponding limit for referred subjects (young or adult) was 3.5–3.8 pmol/1. Broadening of the FT3 reference range was probably brought about by a significant number of patients in the hospital-referred group with the “1OW-T3 syndrome” of mild non-thyroidal illness. Accordingly, FT3 was inferior to FT4 in the discrimination of hypothyroidism, as FT4 was unaffected by this phenomenon. Effects of age and non-thyroidal illness on serum FT3 concentrations require great care when selecting subjects for a laboratory euthyroid reference range typical of the routine workload. Constraints on the choice of subjects for FT4 reference ranges are less stringent.

The Effect of Long-Term Metabolic Control on Free Thyroid Hormone Levels in Diabetics during Insulin Treatment

1987 ◽  
Vol 24 (5) ◽  
pp. 466-469 ◽  
Author(s):  
J H Parr
Keyword(s):  
Thyroid Hormone ◽  
Metabolic Control ◽  
Insulin Treatment ◽  
Density Lipoprotein ◽  
Hdl Cholesterol ◽  
Hormone Levels ◽  
Free Thyroid Hormone ◽  
The Mean ◽  
Thyroid Hormone Levels

Serum concentration of free T3 and, in female patients, FT4, were found to be lower in 20 asymptomatic, moderately-poor or well controlled, diabetics treated with insulin than in a group of non-diabetic subjects. Over a mean 3-month period of the study a significant fall occurred in HbA1 concentration in both groups of diabetics without change in free thyroid hormone levels. The mean capillary blood glucose, fasting free insulin and fasting lipid concentrations, other than high density lipoprotein (HDL) cholesterol, did not change. No correlations were found between the changes in HbA1 and free thyroid hormone concentrations. Improvement in long term metabolic control did not influence free thyroid hormone levels in well controlled and moderately-poor controlled diabetics, taking insulin.

Factors Affecting the Serum Free Thyroxine Levels in Hospitalized Chronic Geriatric Patients

1993 ◽  
Vol 41 (7) ◽  
pp. 742-746 ◽  
Author(s):  
Istvan Szabolcs ◽  
Christoph Ploenes ◽  
Mathias Beyer ◽  
Wolfdieter Bernard ◽  
Jorg Herrmann
Keyword(s):  
Geriatric Patients ◽  
Free Thyroxine ◽  
Factors Affecting ◽  
Serum Free ◽  
Serum Free Thyroxine

scholarly journals Serum Free Thyroxine and Triiodothyronine Concentrations in Subacute Thyroiditis

1980 ◽  
Vol 56 (11) ◽  
pp. 1527-1534
Author(s):  
Katsumi YOSHIDA ◽  
Toshiro SAKURADA ◽  
Nobuko KAISE ◽  
Kazuo KAISE ◽  
Hirofumi KITAOKA ◽  
...  
Keyword(s):  
Free Thyroxine ◽  
Subacute Thyroiditis ◽  
Serum Free ◽  
Serum Free Thyroxine

Free thyroxine assessed with three assays in sera of patients with nonthyroidal illness and of subjects with abnormal concentrations of thyroxine-binding proteins

1993 ◽  
Vol 39 (8) ◽  
pp. 1668-1674 ◽  
Author(s):  
R Docter ◽  
H van Toor ◽  
E P Krenning ◽  
M de Jong ◽  
G Hennemann
Keyword(s):  
Blood Donors ◽  
Reference Range ◽  
Equilibrium Dialysis ◽  
Free Thyroxine ◽  
Serum Samples ◽  
Nonthyroidal Illness ◽  
Nonesterified Fatty Acids ◽  
Thyroxine Binding Globulin ◽  
Control Value ◽  
The Mean

Abstract Three methods for estimating free thyroxine (FT4) in serum were studied: equilibrium dialysis, the SPAC-ET FT4 radioimmunoassay kit, and the Amerlite MAB FT4 luminometric assay. Serum samples from 10 subjects with above-normal thyroxine-binding globulin (TBG), 6 with low TBG, 30 with familial dysalbuminemic hyperthyroxinemia (FDH), 13 with nonesterified fatty acids (NEFA) concentrations in serum > 1.0 mmol/L, and 178 patients with various degrees of nonthyroidal illness (NTI) were measured and compared with samples from 42 euthyroid blood donors. The Amerlite MAB FT4 assay compared well with equilibrium dialysis, whereas the SPAC-ET assay averaged 40% lower. All three assays were not influenced by changes in TBG and showed no or only little changes in the presence of NEFA. Mean FT4 values in the FDH samples were somewhat higher than in controls when measured with the SPAC-ET assay, about equal with equilibrium dialysis, and somewhat below the mean control value with the Amerlite MAB FT4 assay, although individual results were within the control reference range. In NTI patients, no FT4 values were below the control reference range by the Amerlite MAB FT4 assay, 4 of 178 were below this range by equilibrium dialysis, and 1 of 178 was below this range by the SPAC-ET assay. In all assays a large proportion of the NTI samples showed FT4 values above the control reference range, a result that will interfere with the efficacy of these assays for assessing thyroid function in NTI patients.

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