Circadian rhythm of blood cardiac troponin T concentration

Introduction High-sensitivity cardiac troponin assays have significantly improved the sensitivity of myocardial infarction detection by using cutoff values and early absolute changes. However, variation in repeated measures also depends on biological variability. This study aimed to assess the potential circadian component of this biological variability. Methods 17 healthy volunteers were recruited, and standardized conditions for physical activity, meals, exposure to light and duration of sleep were imposed. Blood samples were collected every 4 h and high-sensitivity troponin T assay with a limit of detection of 3 ng/l and a 99th percentile of 14 ng/l were used. Circadian variations were analyzed using the cosinor method. Results Statistically significant circadian variations were observed for body temperature, heart rate, and systolic/diastolic arterial blood pressures ( p