Misleading FT4 and FT3 Due to Immunoassay Interference From Autoantibodies
| Autor: | Adam J. McShane, Travis Goettemoeller, Pratibha Rao |
|---|---|
| Rok vydání: | 2022 |
| Předmět: |
Thyroid Hormone Resistance Syndrome
endocrine system medicine.medical_specialty endocrine system diseases Heterophile Clinical Biochemistry Levothyroxine Thyrotropin Octreotide Thyroid Function Tests Internal medicine Humans Medicine Pituitary Neoplasms Diagnostic Errors Aged Autoantibodies Immunoassay Triiodothyronine medicine.diagnostic_test business.industry Thyroid Autoantibody General Medicine Thyroxine medicine.anatomical_structure Endocrinology Female business hormones hormone substitutes and hormone antagonists medicine.drug Hormone |
| Zdroj: | Clinical Biochemistry. 101:16-18 |
| ISSN: | 0009-9120 |
| DOI: | 10.1016/j.clinbiochem.2021.11.015 |
| Popis: | Background Immunoassays used to measure total and free thyroxine (T4 and FT4) and total and free triiodothyronine (T3 and FT3) can provide inaccurate results due to interference from endogenous autoantibodies. Case Report: A 74-year-old female treated for hypothyroidism with levothyroxine replacement had elevated thyroid stimulating hormone (TSH), FT4, and FT3. Due to concern for hyperthyroidism, levothyroxine was discontinued and further workup was initiated. A pituitary MRI revealed a microadenoma but the alpha-subunit was normal. She was given octreotide for suspected TSH secreting pituitary adenoma without improvement in her TSH, FT4, or FT3 levels. She was referred to our clinic, where inaccurate lab values for FT4 and FT3 were suspected. Results Testing via equilibrium dialysis liquid chromatography tandem mass spectrometry (LC-MS/MS) method revealed lower levels of FT4 and FT3. Subsequent testing included heterophile blocking tube treatment, polyethylene glycol (PEG) precipitation, and anti-T3/T4 autoantibody levels. The tests revealed thyroid hormone autoantibodies (THAAs) as the cause of immunoassay interference. Conclusions When thyroid hormones are elevated and TSH is not suppressed, confirmatory testing with another method such as equilibrium dialysis LC-MS/MS, which is not susceptible to interference from autoantibodies, should be considered. |
| Databáze: | OpenAIRE |
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