WHY IS CK-MB HIGH IN A WELL PATIENT?
STEVE BLITZER, MD, of Thornhill, ON, inquires: "What would cause an elevated CK-MB level in a well patient?" He explains, "I ordered CK for baseline screening with a statin drug on a patient who had chronic back pain. The lab which found the CK elevated 'automatically' did the MB fraction and it was high, but the patient was fine. I repeated the test a month later and got the same result."
CK-MB (creatine kinase MB isoenzyme) is said to be specific for the heart -- and infarct- induced damage -- but there are always exceptions to the rule. In a patient with a continued CK-MB-positive fraction, I'd consider a cardiac evaluation to make sure the patient doesn't have a cardiomyopathy, such as myocarditis. An echocardiogram would be an important part of such a work-up. Then again, patients with false positive results do crop up -- and that's a very likely possibility in this case. GC