Falsely elevated thyroid-stimulating hormone results dueto Interference by M-component of IgG-lambda type

• Heterophilic antibodies but also M-components can interfere with laboratory tests causing erroneous results. We report the case of a 75-year-old man with myeloma and a monoclonal immunoglobulin component (M-component) that caused elevated thyroid-stimulating hormone (TSH) results. The M-component was of the IgG-lambda type. Thyroid markers were analyzed repeatedly, and there was a clear association between IgG concentrations and TSH values (R 2 = 0.724). The highest TSH value was 75 mIU/L. Polyethylene glycol (PEG) precipitation of intact immunoglobulins was used to investigate if there was an antibody-related interference problem. The PEG treatment normalized the TSH value, showing that the cause of the elevated TSH result was due to interference caused by the M-component. In conclusion, it is important to remember that both heterophilic antibodies and M-components may cause erroneous results.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Hematologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Hematology (hsv//eng)

Nyckelord

Erroneous laboratory test result

M-component

Myeloma

PEG

precipitation

Thyroid-stimulating hormone

Publikations- och innehållstyp

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