Table 2.

Analytical characteristics of high-sensitivity methods used to determine hs-cTn.

Analytical characteristic	Definition and description	Remarks
LoB	Lowest signal generated in a sample without troponin	Lower values are desirable
LoD	Value obtained in a sample with the lowest concentration of troponin	Lower values are desirable
LoQ	Lowest concentration of troponin that can be determined with acceptable repeatability and reproducibility (a <10% error)	Lower values are desirable
99th percentile (general)	Troponin concentration detected in 99% of truly healthy individuals	1% of truly healthy individuals can have false-positive results, for unknown reasons
99th percentile (sex-specific)	Troponin concentration detected in 99% of truly healthy individuals, taking into account the sex	In men, the 99th percentile upper limit is about 1.5-2 times higher than that in women
Cut-off value	Minimum troponin concentration for diagnosis of AMI	The level of 99th percentile is used as a reference
CV%	Random variation of measurements in the same sample	(i) <10% (preferred)—high precision (ii) 10-20% (acceptable)—nonhigh accuracy (iii) >20% (unacceptable)—inaccurate
Percentile values < 99th percentile in healthy subjects	Number of healthy individuals with detected troponin level in blood	Values range between LoD and the 99th percentile
99th percentile/LoD ratio		(i) <1 (acceptable)—highly sensitive (ii) >10—extremely sensitive (iii) >20—ultrasensitive

LoB = limit of blank; LoD = limit of detection; LoQ = limit of quantitation; CV% = coefficient of variation; AMI = acute myocardial infarction; hs-cTn = high-sensitivity cardiac troponins.