Higher Levels of Creatine Kinase MB (CK-MB) Than Total Creatine Kinase (CK): A Biochemistry Reporting Error or an Indicator of Other Pathologies?

Abstract

The creatine kinase (CK) enzyme and its isoenzymes hold significant diagnostic value, appearing in distinct patterns across various tissues. The most common method for creatine kinase MB (CK-MB) estimation is based on immunoinhibition. However, this method can report falsely elevated CK-MB levels in various scenarios. Persistently elevated CK-MB levels or discrepancies between measured values and the patient's clinical condition warrant further investigation, such as total CK isoenzyme electrophoresis. This report presents a case where a patient was diagnosed with acute myocardial infarction and treated according to established guidelines. However, the presence of abdominal pain, in addition to persistently elevated CK-MB after the resolution of cardiac symptoms and a higher CK-MB to total CK ratio, suggested alternative pathologies. Thorough laboratory investigations, including quantitative CK isoenzyme electrophoresis and contrast-enhanced computed tomography (CECT) of the abdomen, followed by emergency operative intervention, led to a secondary diagnosis of acute small bowel infarction.

Keywords: acute myocardial injury; ckmb; creatine kinase; immunoinhibition; small-bowel injury.

Figure 1. ECG of the patient showing changes suggestive of anterior wall myocardial infarction.

Figure 2. Image of pre-PCI and post-PCI angiography.

All the identities of the patient and cath lab have been removed for potential conflict of interest. PCI: Percutaneous coronary intervention.

Figure 3. Image of CT scan of abdomen showing SMA occlusion.

All the identities of the patient and the imaging centre have been removed for potential conflict of interest. SMA: Superior mesenteric artery.