Postgraduate medical journal
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Case Reports
Falsely raised TSH levels due to human anti-mouse antibody interfering with thyrotropin assay.
The case of a 39-year-old woman who was referred for weight gain and amenorrhoea is reported. Laboratory evaluation showed high levels of thyroid-stimulating hormone (TSH). ⋯ Evaluation at another laboratory showed normal levels of TSH, raising the possibility of interfering substances. TSH levels were normalised with the addition of mouse serum to the patient's sample, confirming the presence of human anti-mouse antibodies as the interfering substance in the TSH assay.