Falsely elevated cardiac troponin I levels

Area of Science:

• Cardiology
• Clinical Chemistry
• Immunology

Background:

• Cardiac troponins (cTn) are crucial biomarkers for diagnosing acute coronary syndrome.
• Elevated cTn levels can be observed in conditions other than myocardial infarction, such as pulmonary embolism, myocarditis, and sepsis.
• Immunoassay measurements for analytes like cTn can be affected by endogenous or exogenous antibodies.

Observation:

• A 48-year-old male with hypercholesterolemia and obesity presented with chest pain and elevated troponin I (TnI) levels on two occasions.
• The elevated TnI levels were investigated for potential interference.
• The patient's blood sample showed normal cTnI levels when pre-treated with polyethylene glycol to inactivate interfering antibodies.

Findings:

• The patient's elevated TnI levels were determined to be spuriously elevated.
• Heterophile antibodies, rheumatoid factor, or other autoantibodies were identified as the likely cause of interference in the Abbot AxSYM cTnI assay.
• Polyethylene glycol precipitation effectively inactivated the interfering antibodies, confirming the spurious nature of the initial TnI results.

Implications:

• Spurious elevations in cardiac troponin levels can lead to misdiagnosis and unnecessary interventions.
• Understanding potential antibody interference is critical for accurate interpretation of immunoassay results.
• Clinical laboratories should consider antibody interference as a potential cause of unexpected biomarker elevations, especially when results do not correlate with clinical presentation.