The reference intervals of thyroid stimulating hormone in healthy individuals with normal levels of serum free thyroxine and without sonographic pathologies

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.

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A Case Series of Patients With Central Hypothyroidism From Oxcarbazepine Therapy

Journal of Child Neurology ◽

10.1177/0883073820962926 ◽

2020 ◽

pp. 088307382096292 ◽

Cited By ~ 1

Author(s):

Bahareh Michelle Schweiger ◽

Aaron-James Lao ◽

Jane Tavyev

Keyword(s):

Thyroid Function ◽

Pediatric Population ◽

Case Series ◽

Metabolic Enzymes ◽

Thyroid Stimulating Hormone ◽

Free Thyroxine ◽

Central Hypothyroidism ◽

Serum Free ◽

Serum Free Thyroxine ◽

Stimulating Hormone

Many medications can impact thyroid function. Antiseizure medications have been shown to disrupt thyroid function in adults, but information is limited about how antiseizure medications may affect thyroid function in children. Oxcarbazepine is an analog of carbamazepine designed to minimize effects from the hepatic P450 metabolic enzymes. We have found that in the pediatric population, serum free thyroxine is reduced and thyroid-stimulating hormone concentrations are unchanged in patients taking oxcarbazepine with the mechanism thus being central hypothyroidism.

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Composite Reference Interval for Thyroid-Stimulating Hormone and Free Thyroxine, Comparison with Common Cutoff Values, and Reconsideration of Subclinical Thyroid Disease

Clinical Chemistry ◽

10.1373/clinchem.2009.124560 ◽

2009 ◽

Vol 55 (11) ◽

pp. 2019-2025 ◽

Cited By ~ 8

Author(s):

H Alec Ross ◽

Martin den Heijer ◽

Ad R M M Hermus ◽

Fred C G J Sweep

Keyword(s):

Probability Distribution ◽

Thyroid Disease ◽

Reference Interval ◽

Reference Intervals ◽

Thyroid Stimulating Hormone ◽

Free Thyroxine ◽

Thyroid Peroxidase ◽

Healthy Individuals ◽

Cutoff Values ◽

Stimulating Hormone

Abstract Background: Examination of the 2-dimensional probability distribution of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) shows that the widths of the TSH and FT4 reference intervals derived from this bivariate distribution are mutually interdependent, an aspect commonly ignored when interpreting thyroid testing results with separate reference intervals for TSH and FT4. We desired to establish and critically evaluate a composite reference interval for TSH and FT4 to allow bivariate classification of biochemical thyroid conditions. Methods: FT4 and TSH results of 871 healthy individuals [361 women and 510 men, 18–40 years old, without history of thyroid-related disease or medication, negative for anti–thyroid peroxidase (anti-TPO) antibody] were transformed to standard normal variables by logarithmic transformation with correction for skewness and subsequent normalization. We established a 95% reference interval of the distance of each FT4/TSH pair of values to the center of the 2-dimensional probability distribution. Results: The bivariate 95% reference interval is enclosed by a circular profile with radius 2.45 SD. By contrast, conventional reference intervals comprise a square with the boundaries of −1.96 and +1.96 SD for both FT4 and TSH that enclose only 90% of all data. Compared with the ±1.96 SD square, the bivariate reference interval classified 4% fewer of 3651 healthy individuals older than 40 years as subclinically hyperthyroid and 14% fewer of 712 anti-TPO–positive healthy individuals as subclinically hypothyroid. Conclusions: Conventional application of separate cutoff values for FT4 and TSH leads to overestimation of the incidence of subclinical thyroid disease. Application of a composite overall reference interval is recommended.

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Establishment of Early Pregnancy Related Thyroid Hormone Models and Reference Intervals for Pregnant Women in China Based on Real World Data

Hormone and Metabolic Research ◽

10.1055/a-1402-0290 ◽

2021 ◽

Vol 53 (04) ◽

pp. 272-279

Author(s):

Chaochao Ma ◽

Xiaoqi Li ◽

Lixin Liu ◽

Xinqi Cheng ◽

Fang Xue ◽

...

Keyword(s):

Thyroid Hormone ◽

Thyroid Hormones ◽

Pregnant Women ◽

Early Pregnancy ◽

Gestational Age ◽

Dynamic Change ◽

Reference Intervals ◽

Thyroid Stimulating Hormone ◽

Free Thyroxine ◽

Stimulating Hormone

AbstractThyroid hormone reference intervals are crucial for diagnosing and monitoring thyroid dysfunction during early pregnancy, and the dynamic change trend of thyroid hormones during pregnancy can assist clinicians to assess the thyroid function of pregnant women. This study aims to establish early pregnancy related thyroid hormones models and reference intervals for pregnant women. We established two derived databases: derived database* and derived database#. Reference individuals in database* were used to establish gestational age-specific reference intervals for thyroid hormones and early pregnancy related thyroid hormones models for pregnant women. Individuals in database# were apparently healthy non-pregnant women. The thyroid hormones levels of individuals in database# were compared with that of individuals in database* using nonparametric methods and the comparative confidence interval method. The differences in thyroid stimulating hormone and free thyroxine between early pregnant and non-pregnant women were statistically significant (p<0.0001). The reference intervals of thyroid stimulating hormone, free thyroxine and free triiodothyronine for early pregnant women were 0.052–3.393 μIU/ml, 1.01–1.54 ng/dl, and 2.51–3.66 pg/ml, respectively. Results concerning thyroid stimulating hormone and free thyroxine reference intervals of early pregnancy are comparable with those from other studies using the same detection platform. Early pregnancy related thyroid hormones models showed various change patterns with gestational age for thyroid hormones. Early pregnancy related thyroid hormones models and reference intervals for pregnant women were established, so as to provide accurate and reliable reference basis for the diagnosing and monitoring of maternal thyroid disfunction in early pregnancy.

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