Chonnam Med J.  2011 Apr;47(1):48-50. 10.4068/cmj.2011.47.1.48.

A Case of a False-Positive Anti-Myeloperoxidase Antibody ELISA in a Patient with Hypothyroidism

• Jin MK
• Seo KY
• Kang JY
• Choi JY
• Yoon SH
• Kim YL
• Won DI
• Park SH

• KMID: 2172246
• DOI: http://doi.org/10.4068/cmj.2011.47.1.48

Abstract

We present a case of a false-positive anti-myeloperoxidase (MPO) antibody result on an ELISA in a patient with anti-thyroid microsomal antibody (TMA)-positive hypothyroidism. A 41-year-old woman presented with dyspnea on exertion. The initial evaluation revealed pericardial effusion associated with hypothyroidism. In addition, microscopic hematuria with normal renal function and positive cytoplasmic anti-neutrophil cytoplasmic antibodies (c-ANCA) on immunofluorescent assay were found. In further evaluation, elevated anti-TMA and MPO antibodies by ELISA. While no definite signs of vasculitis were present, the clinical state improved with thyroid hormone replacement and diuretics. Anti-MPO antibody was still positive in the follow-up tests, and microscopic hematuria persisted. On the basis of previous reports that thyroid peroxidase and MPO molecules contain cross-reactive epitopes that are exposed in denaturated molecules, we suggest that in a patient with anti-TMA-positive hypothyroidism, anti-MPO antibody might also be positive on ELISA without clinical signs of vasculitis.

Keyword

Hypothyroidism; Anti-thyroid peroxidase antibodg; Anti-myeloperoxi dase antibody

MeSH Terms

Adult
Antibodies
Antibodies, Antineutrophil Cytoplasmic
Cytoplasm
Diuretics
Dyspnea
Enzyme-Linked Immunosorbent Assay
Epitopes
Female
Follow-Up Studies
Hematuria
Humans
Hypothyroidism
Iodide Peroxidase
Pericardial Effusion
Thyroid Gland
Vasculitis
Antibodies
Antibodies, Antineutrophil Cytoplasmic
Diuretics
Epitopes
Iodide Peroxidase

Figure

• 

  FIG. 1 Clinical status and laboratory findings of ANCA, anti-MPO antibody, and anti-TMA. C-ANCA: cytoplasmic anti-neutrophil cytoplasmic antibodies, Anti-TMA: anti-thyroid microsomal antibody, Anti-MPO Ab: anti-myeloperoxidase antibody.

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