Medications that distort in vitro tests of thyroid function, with particular reference to estimates of serum free thyroxine

Stockigt, Jim; Lim, Chen‐Fee

doi:10.1016/j.beem.2009.06.004

Cited by 71 publications

(42 citation statements)

References 50 publications

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“…The presence of heterophile antibodies (produced as a result of close contact with animals) can potentially interfere with the TSH assay, causing either a falsely high or falsely low result. 39 Therefore, it is plausible that a truly elevated TSH could be falsely lowered into the normal range by the presence of heterophile antibodies. Resistance to thyroid hormone (RTH) is a rare condition generally caused by a mutation in the thyroid hormone receptor β gene resulting in elevated levels of free T3 and free T4, but a normal (or slightly elevated) TSH.…”

Section: Other Conditionsmentioning

confidence: 99%

Biochemical Testing of the Thyroid: TSH is the Best and, Oftentimes, Only Test Needed – A Review for Primary Care

Sheehan

2016

Clin Med Res

148

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Disorders of thyroid function are common, and screening, diagnosis, and management are often performed by primary care providers. While management of significant biochemical abnormalities is reasonably straight forward, laboratory tests only slightly outside, or even within, the normal range are becoming more difficult to appropriately manage. A large part of this increasing difficulty in appropriate management is caused by patients requesting, and even demanding, certain tests or treatments that may not be indicated. Symptoms of thyroid dysfunction are non-specific and extremely prevalent in the general population. This, along with a growing body of information available to patients via the lay press and internet suggesting that traditional thyroid function testing is not reliable, has fostered some degree of patient mistrust. Increasingly, when a physician informs a patient that their thyroid is not the cause of their symptoms, the patient is dissatisfied and even angry. This review aims to clarify the interpretation of normal and mild abnormalities of thyroid function tests by describing pituitarythyroid physiology and through an in depth review of, arguably, the three most important biochemical tests of thyroid function: TSH, free T4, and anti-TPO antibodies. It is important for primary care providers to have an understanding of the shortcomings and proper interpretation of these tests to be better able to discuss thyroid function with their patients.

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Section: Other Conditionsmentioning

confidence: 99%

Biochemical Testing of the Thyroid: TSH is the Best and, Oftentimes, Only Test Needed – A Review for Primary Care

Sheehan

2016

Clin Med Res

148

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“…Since in the literature it was suggested that the use of platelet aggregation inhibitors could influence FT 4 levels [12], we also performed our analyses with the use of any platelet aggregation inhibitor added to the model. However, this did not change our results.…”

Section: Discussionmentioning

confidence: 99%

Plasma Levels of Free Thyroxine and Risk of Major Bleeding in Bariatric Surgery

et al. 2016

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Background: In a recent study of patients using vitamin K antagonists, those with low free thyroxin (FT₄) levels within the normal range had a 3- to 5-fold increased risk of major bleeding. We tested the hypothesis that low levels of preoperative FT₄ within the reference range are associated with an increased risk of major bleeding during and after bariatric surgery. Methods: The charts of 2,872 consecutive patients undergoing bariatric surgery were retrospectively screened for bleeding episodes. Patients with major bleeding until 1 month after surgery were compared to randomly selected control patients without bleeding, in a ratio of 1:4. We evaluated the association between preoperative FT₄ levels and the risk of major bleeding by logistic regression. Results: Seventy-two cases(2.5%) withmajor bleeding were identified and 288 controls were selected. The median plasma level of FT₄ was 13 pmol/l (interquartile range: 12-14) in the cases as well as in the controls. No clear effect was observed of low levels of FT₄ on the risk of major bleeding: odds ratio 1.48 (95% CI: 0.46-4.80) for patients with an FT₄ level <11 pmol/l, 1.03 (0.49-2.18) for patients with an FT₄ level <12 pmol/l, and 1.12 (0.65-1.94) for patients with an FT₄ level <13 pmol/l as compared to patients with FT₄ values greater than or equal to these cutoff levels. Interpretation: We did not observe an increased risk of major bleeding with low levels of FT₄ in patients undergoing bariatric surgery.

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“…Serum TSH was measured with a commercially available immunoradiometeric assay and total T4 and total T3 were determined with commercial radioimmunassays, all from Beckman Coulter (Immunotech, Czech Republic). As blood samples of ICU patients were always taken via heparinized lines, free hormone concentrations were not determined because these would give artefactuous results (32). We used a commercially available radioimmunoassay to quantify serum rT3 concentrations (ZenTech, Angleur, Belgium).…”

Section: Quantification Of Circulating Hormones Metabolites and Bindmentioning

confidence: 99%

Circulating 3-T1AM and 3,5-T2 in Critically Ill Patients: A Cross-Sectional Observational Study

Langouche

Lehmphul

Perre

et al. 2016

Thyroid

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Medications that distort in vitro tests of thyroid function, with particular reference to estimates of serum free thyroxine

Cited by 71 publications

References 50 publications

Biochemical Testing of the Thyroid: TSH is the Best and, Oftentimes, Only Test Needed – A Review for Primary Care

Biochemical Testing of the Thyroid: TSH is the Best and, Oftentimes, Only Test Needed – A Review for Primary Care

Plasma Levels of Free Thyroxine and Risk of Major Bleeding in Bariatric Surgery

Circulating 3-T1AM and 3,5-T2 in Critically Ill Patients: A Cross-Sectional Observational Study

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