Avoiding Misdiagnosis Due to Antibody Interference with Serum Free Thyroxin

Abstract

IntroductionInterfering antibodies are capable of causing potentially misleading results in automated thyroid hormone immunoassays.Case PresentationWe report the case of a 46- year-old female patient with autoimmune hypothyroidism in chronic replacement treatment with levothyroxine who was presented 8 years after diagnosis with a thyroid function test showing an increased level of TSH and a very high level of FT4. Interference in the laboratory serum free thyroxin (FT4) test was suspected, due to the lack of symptoms of hyperthyroidism and a different immunoassay platform confirmed a low FT4 result. The discrepancy between the two results was explained by the presence of antiT4-autoantibodies.ConclusionsAntibody interference with serum free thyroxine must be considered when clinical findings and laboratory results show discrepancies.

Hormone Immunoassay Interference: A 2021 Update

“…In vivo, the free thyroid hormone Ab seems to behave like another endogenous binding protein. The frequency of anti-T4 and anti-T3 autoAbs specifically relates to autoimmune thyroid disorders such as Hashimoto thyroiditis and other autoimmune diseases (e.g., lupus erythematosus, vitiligo) [80,[83][84][85][86]. These autoAbs can be induced by interferon-α therapy or can be transient and associated with Epstein-Barr-virus infection [87,88].…”

Clinical Consequences of Variable Results in the Measurement of Free Thyroid Hormones: Unusual Presentation of a Family with a Novel Variant in the <b><i>THRB</i></b> Gene Causing Resistance to Thyroid Hormone Syndrome

“…To demonstrate the presence of an assay artifact, we first reassessed TFTs with a one-step assay (electrochemiluminescence immunoassay, Roche Elecsys, Mannheim, Germany) and with a two-step method (Wallac DELFIA Perkin-Elmer) both confirming the biochemical feature of central hyperthyroidism (Table 1). As proband’s serum had been reported to us to potentially contain anti-T4 and anti-T3 antibodies on a radioimmunoprecipitation technique [10], we performed a polyethylene glycol (PEG) precipitation test, described by Beato-Víbora and Alejo-González [11], to exclude interference by circulating immunoglobulins on TFTs.…”

Correlation of hormonal and cytokines regulation in case of autoimmune thyroiditis

“…Лечение гипотиреоза на фоне АИТ сводится в основном к использованию заместительной тера-пии тиреоидными гормонами (ТГ) в случае его мани-фестации [4,7]. Однако по современным представле-ниям ТГ отводят роль антигенов в патогенезе ауто-иммунного воспаления ЩЖ [5,8,9], из чего следует, что заместительная терапия в этих случаях может поддерживать персистенцию аутоиммунного про-цесса, в том числе при IgG4-обусловленном тирео-идите, когда наиболее важное значение приобретает взаимодействие В-и Т-клеток с клетками врожден-ного иммунитета [1,4,5,10]. АИT относится к за-болеваниям, при котором аутоиммунное воспаление опосредовано прежде всего Т-клетками, а точная роль В-клеток в его патогенезе также остается до сих пор неясной [2][3][4].…”