Negative interference of bilirubin and hemoglobin in the MEIA troponin I assay but not in the MEIA CK‐MB assay

Abstract

Troponin I is a sensitive and specific marker for the diagnosis of myocardial infarction. Several commercially available immunoassays measure the concentration of troponin I in serum. The microparticle enzyme immunoassay (MEIA) for troponin I (Abbott Laboratories, Abbott Park, IL) is widely used in clinical laboratories, including our hospital laboratory. We studied the effect of bilirubin and hemolysis on the MEIA for troponin I and compared our assay with a newly available chemiluminescent assay (CLIA) for troponin I (Bayer Diagnostics, Tarrytown, NY). We also measured CK-MB concentration using the MEIA CK-MB assay. One serum pool was prepared by combining several specimens of one patient with elevated troponin I and with a diagnosis of myocardial infarction. Other serum pools were prepared by combining sera with similar troponin I values. All serum pools showed normal bilirubin concentrations and had no hemolysis. Then we supplemented aliquots of serum pools with various concentrations of bilirubin (5.0, 10.0, 15.0, and 20.0 mg/dL). After supplementation, troponin I concentrations were measured again using the MEIA and CLIA. We observed a statistically significant decrease in troponin I concentration in the presence of bilirubin with the MEIA. For example, in serum pool 1, the troponin I concentration was 16.3 (bilirubin: 0.8 mg/dL). In the presence of 5.0, 10.0, 15.0 and 20.0 mg/dL of added bilirubin, the cardiac troponin I concentrations were 13.9, 13.4, 13.3 and 13.0 ng/ml respectively. We observed similar negative interference of bilirubin in troponin I measurement by the MEIA in other pools. The troponin I value decreased slightly (not statistically significant) in one pool and did not change in two other pools in the presence of bilirubin when we measured troponin I concentration using the CLIA. Interestingly, bilirubin did not interfere with the MEIA CK-MB assay. Moderate hemolysis did not have any effect on the troponin I assay using either the MEIA or CLIA. However, gross hemolysis (hemoglobin > 40 mg/dL) interfered with both assays for troponin I.

Effects of hemolysis on the assays of serum CK, CK-MB activities and CK-MB (MASS), troponin and myoglobin measurments

“…It has been previously demonstrated that hemolysis has less effect on mass assays than activity based methods but the degree and the direction of this interference is still contradictory in the literature [23]. Many studies has claimed that hemolysis has not any effect on mass assays except at very high Hb values [24][25][26]. In contrast, Donnely detected positive interference due to hemolysis in CK-MB mass assays [27].…”

Negative Interference in Cardiac Troponin I Immunoassays from a Frequently Occurring Serum and Plasma Component

“…They may also result from fluid therapy given to patients (28 ). One report of a false-negative cTnI result was attributed to circulating cTnI autoantibodies (29 ), and bilirubin and hemoglobin have been reported to cause negative interference in certain cTnI assays (30 ).…”

Negative Interference in Cardiac Troponin I Immunoassays by Circulating Troponin Autoantibodies

“…Numerous assaydependent false-positive results for troponin assays have been reported, the majority of which were caused by heterophilic antibodies (17 ) or rheumatoid factor (18 -20 ). False-negative results have been attributed to bilirubin, hemoglobin (21 ), and in one case, to circulating cTnI autoantibodies (22 ). When performing recovery studies with a cTnI immunoassay, we previously observed frequent negative interference from a serum-and plasmaderived component found in both healthy individuals and patients with acute coronary syndromes (23 ).…”