Abstract:Background: Copeptin, a marker of vasopressin production, has been introduced for earlier diagnosis of acute myocardial infarction and other clinical emergencies. We evaluated the analytical performance of a new generation copeptin assay in an inter-laboratory trial.Methods: Precision, linearity range, carry-over contamination, the limit of blank and an inter-laboratory comparison trial for the copeptin US KRYPTOR assay were performed on the B·R·A·H·M·S KRYPTOR compact PLUS.Results: The intra-assay imprecision (CVs) was 12.6-2.2% and total imprecision over five days was 12.3-4.3% between 3.1 and 18.2 pmol/L. The assay had excellent linearity between 7-222 pmol/L. The limit of blank was 2.5 pmol/L and the limit of detection was 3.2 pmol/L, but was dependent on the analyte-free material used. No significant difference between sample type, such as serum or different types of plasma or reagent lots, was noted. The copeptin results remained unchanged upon five repeated freeze-thaw cycles. A set of patient samples with a mean copeptin concentration of 2.1-61 pmol/L run at two separate sites showed close correlation (r 2 =0.99, slope=1.01, intercept=0.35), indicating comparable results across laboratories.
Conclusion:The new ultrasensitive copeptin KRYPTOR assay shows excellent inter-lab precision, opening up the possibility for international guidelines to exclude acute myocardial infarction.