Creatine Kinase-MB The Journey to Obsolescence

Objectives: To evaluate the clinical utility of and demand for the creatine kinase (CK)-MB assay. Methods: We examined the number of CK-MB tests from 2007 through 2013 while we progressively deemphasized their use. We first removed CK-MB from the acute coronary syndrome (ACS) panel and then from the main menu and observed the demand for the test. We also reviewed patient medical records to assess the appropriateness of its use. Results: After removing CK-MB from the ACS panel, the test volume dropped from around 12,000 per year to about 150 per year. In reviewing the records of 171 patients who had CK-MB determination done over a 28-month period, we discovered that CK-MB contributed to the diagnosis in only one patient, although it was not essential. Since removing CK-MB from the laboratory menu, two CK-MB tests were ordered in 4 months, and neither added value. Conclusions: CK-MB determinations do not add value to information available from the troponin assay and can be safely removed from the laboratory menu.