The 99th percentile values of six cardiac troponin assays established for a reference population using strict selection criteria.

BACKGROUND: Since the 99th percentile reference limit for cardiac troponin (Tn) can vary depending on the reference population, Sandoval et al. published systematic selection criteria. In this study, these systematic criteria were applied for the first time to obtain the 99th percentile reference limits for 6 Tn tests. METHODS: The reference population was selected in accordance with the systematic criteria, and reference limits were set with respect to the six types of Tn assays. The coefficient of variation (CV) at the reference limit was determined using 3-4 concentrations of frozen serum. RESULTS: In total, 641 South Koreans (303 males, 338 females) were selected as the reference population. The 99th percentile reference limit of Tn in the six assays ranged from 13.4 to 34.2pg/ml. The measurable fractions among the reference population ranged from 1.3% to 80.5%. The CVs at the reference limit ranged from 5.3% to 43.0%, and three were <10%. CONCLUSIONS: In this study, a reference population was selected for the first time in accordance with the systematic criteria of Sandoval et al., and the reference limit for South Koreans was established. The values obtained in this study are different from those proposed by manufacturers, which confirms the importance of having a reference population. Four out of six assays did not fulfill the criteria for high-sensitivity tests.