A Macro-TSH: A Clinical Diagnostic Dilemma

Xikombiso Nkuna; Zodwa Dire; Siyabonga Khoza

A Macro-TSH: A Clinical Diagnostic Dilemma

EJIFCC. 2022 Dec 12;33(4):317-324. eCollection 2022 Dec.

Authors

Xikombiso Nkuna¹, Zodwa Dire², Siyabonga Khoza¹

Affiliations

¹ Department of Chemical Pathology, National Health Laboratory Service and University of the Witwatersrand, Johannesburg, South Africa.
² Division of Endocrinology, Department of Internal Medicine, School of Clinical Medicine and University of the Witwatersrand, Johannesburg, South Africa.

PMID: 36605299
PMCID: PMC9768619

Abstract

Isolated increase in thyrotropin stimulating hormone (TSH) in a clinically euthyroid patient may be caused by the formation of a macromolecule between TSH and autoantibodies causing discordant thyroid function test results. Despite the effort to eliminate interferences in immunoassays, these assays are still vulnerable to different interferences. Immunoassay interferences may cause erroneous results and lead to misdiagnosis which may subject a patient to unnecessary investigations and treatment. Immunoassays are affected by multiple substances; these may be endogenous or exogenous such as heterophile antibodies, autoantibodies, macromolecules, and human anti-mouse antibodies. This case reports a 47-year-old African woman who presented with a persistent elevated TSH with thyroid hormones within normal reference limits. She was found to have a macro-TSH which was associated with IgA paraprotein.

Keywords: immunoassays; interferences; macroTSH.

Publication types

Case Reports