A note on False positive Troponin I due to RF

Troponin complex is located on the thin filament of skeletal and myocardial muscle. The high sensitivity and specificity of cardiac troponin to detect myocardial injury is well documented. However, various factors can interfere with the TnI assay, leading to falsely elevated levels. This include particularly rheumatoid factor (RF).

Rheumatoid factor causes interference in the immunoassays. 5% of healthy people may have circulating rheumatoid factor, and approximately 1% of patients with elevated cardiac TnI levels may have this elevation solely because of the rheumatoid factor.


References:

1. Schifman, RB, James, SH, Sadrzadeh, SMH, et al Between-assay variation in false positive troponin I measurements in patients on renal dialysis or with positive rheumatoid factor - Clin Chem 1999;45,A145

2. Krahn, J, Parry, DM, Leroux, M, et al High percentage of false positive cardiac troponin I results in patients with rheumatoid factor. Clin Biochem 1999;32,477-480