Related Experiment Videos
Multiple spuriously abnormal thyroid function indices due to heterophilic antibodies
T M Fiad1, J Duffy, T J McKenna
1Department of Endocrinology, St Vincent's Hospital, Dublin, Ireland.
Clinical Endocrinology
|September 1, 1994
Summary
Interfering immunoglobulins in patient serum caused falsely elevated thyroid hormone levels (free T4, total T4, total T3) and thyroid-stimulating hormone (TSH) in lab tests.
Area of Science:
- Clinical Biochemistry
- Endocrinology
- Immunology
Background:
- Thyroid function tests are crucial for diagnosing thyroid disorders.
- Enhanced chemiluminescent immunoassays are commonly used for thyroid hormone measurement.
- Patient presented with weight loss, prompting thyroid function assessment.
Observation:
- Initial thyroid function tests showed elevated free T4 (FT4), total T4 (TT4), total T3 (TT3), and TSH.
- The patient appeared euthyroid despite abnormal lab results.
- Serum re-analysis after immunoglobulin precipitation revealed normal T4 and T3 levels.
Findings:
- Non-specific immunoglobulins in the patient's serum cross-reacted with assay antibodies, causing artefactual elevations.
- Anti-immunoglobulin antibodies neutralized these interfering substances.
- This is the first reported case of artefactual elevation across multiple thyroid assays due to interfering immunoglobulins.
Implications:
- Interfering immunoglobulins can lead to misdiagnosis of thyroid dysfunction.
- The phenomenon may be more common than recognized, especially when affecting single assays.
- Awareness and appropriate diagnostic measures are necessary to detect such interferences.