High-Dose Hook Effect in an Immunochromatography–Optical Quantitative Reader Method for Myoglobin

Triaging of patients with chest pain to rule out acute myocardial infarction is important. Myoglobin is thought to be an effective marker for this purpose in the early hours after the onset of symptoms because it is released into the blood shortly after myocardial damage (1)(2)(3). The Cardiac Reader (Roche) provides a platform for the quantitative immunologic measurement of whole-blood myoglobin. The measuring range of the Cardiac Reader for myoglobin is 30–700 μg/L, and the upper reference limit is 80 μg/L. In a previous study, the within-series CV (the mean value of 20 within-run CVs with 20 instruments) was 5–10% and was almost constant throughout the measuring range (4). The assay system is thought to be suitable for near-patient use because of its easy operation and the short assay time. We observed two cases whose blood myoglobin concentrations showed falsely low values with this method. Case A was an 84-year-old male in cardiogenic …