High sensitive cardiac troponin: biological variation, circadian rhythm and diagnostic algorithms

Abstract

The biological variation of cardiac troponins and the existence of a circadian/diurnal rhythm have been poorly evaluated as only the recently developed high-sensitivity assays (hs-cTn) allow the detection of circulating concentrations of both cardiac troponin I (cTnI) and T (cTnT) in reference subjects and under the cut-off values. Available data seem to demonstrate a circadian rhythm for cTnT but not for cTnI but these data need to be confirmed and in particular it should be better clarified if possible variation may affect currently recommended rapid diagnostic algorithms for safe rule-in and rule-out strategies. Here we report the results obtained using a hs-cTnI assay in 35 subjects who underwent serial samples collection over time.

Keywords

• Cardiac troponins
• biological variation
• diurnal rhythm
• rapid diagnostic algorithm
• reference change value
• index of individuality