KLK3 and myocardial infarction: The PSA levels after surgery are typically near zero, andit is necessary to monitor even small changes in PSA concentrationon the scale of picograms as an indication of cancer recurrence.42 Human cardiac troponin (cTn) is a biomarkerof myocardial infarction.43 Healthy individualshave cTn blood concentrations of 1 to 50 pg/mL.