{"id":"ck-mb","name":"CK-MB","shortName":"CK-MB","aliases":["CKMB","Creatine Kinase MB","CK-MB Mass","CK-MB, Serum","CPK-MB","CK MB Isoenzyme","Creatine Kinase-MB","Creatine Kinase, MB Isoenzyme","CK-MB Isoenzyme","Creatine Phosphokinase MB","CK-MB (Mass)","CK-2","CPK-2"],"abbreviations":["CK-MB","CKMB","CPK-MB"],"loinc":[{"code":"13969-1","primary":true},{"code":"83092-7","primary":false}],"specimen":"serum-or-plasma","units":[{"ucum":"ng/mL","display":"ng/mL"},{"ucum":"ug/L","display":"µg/L"}],"referenceRanges":[{"population":"Adults","low":0,"high":5,"unit":"ng/mL","unitDisplay":"ng/mL","note":"CK-MB mass has no single standard interval. Each assay maker sets its own upper limit, and this one is the Siemens Atellica IM CK-MB decision threshold of 5 ng/mL, as quoted in a 2026 peer-reviewed comparison paper. It is a decision limit, not a central 95% interval, and a result of exactly 5 is not above it. In a separate 2025 assay-evaluation study of 262 healthy adults on a different assay, the upper limits were about 3.9 ng/mL overall, higher in men (about 4.5 to 5.1 ng/mL) than in women (about 2.4 to 2.7 ng/mL), so a limit below 5 is common, especially for women. Always compare your result with the range printed on your own report.","sources":[{"title":"Preliminary comparative evaluation of an immunofluorescence point-of-care system and central laboratory platforms for measuring cardiac biomarkers","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC13122200/","publisher":"Practical Laboratory Medicine","year":2026},{"title":"Evaluation of the Analytical Performance of a High-Precision Immunoassay for the Creatine Kinase-MB Isoenzyme","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12690225/","publisher":"Cureus","year":2025}]}],"review":{"status":"ai-draft","label":"AI-drafted. Awaiting verification","lastReviewed":"2026-10-03"},"summary":"A heart-muscle form of the enzyme creatine kinase. It was long used to look for heart muscle injury, and troponin has now mostly replaced it.","url":"https://bloodtesttracker.com/markers/ck-mb","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}