Twenty-Four-Hour Biological Variation Profiles of Cardiac Troponin I in Individuals with or without Chronic Kidney Disease

To the Editor: The interpretation of cardiac troponin concentrations at presentation and their dynamics over time is a key aspect in the diagnostic workup of acute myocardial infarction in the absence of characteristic electrocardiogram abnormalities. The present biological variation study sought to examine and compare the hour-to-hour biological variation in cardiac troponin I (cTnI) over 24 h in individuals with and without chronic kidney disease (CKD).1 This study was carried out according to the principles of the Declaration of Helsinki and approved by the Institutional Review Board and Ethics Committee of Maastricht University Medical Center (clinicaltrials.gov: NCT02091427 and NCT02210897). All participants provided written informed consent. From 8:30 AM until 9:30 AM the next day, 20 individuals with clinically stable CKD stage 3 or higher (estimated glomerular filtration rate (eGFR) <59 mL · min−1 · 1.73 m−2) and 20 individuals without CKD were restricted to the laboratory environment. All individuals were of Caucasian ethnicity. Every hour during 24 h, …