This Article  • Full text  • PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Contact me when this article is cited  Related Content  • Similar articles in JAMA

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

To the Editor.—Dr Mahalingam and Ottlinger¹ report the case of an elderly patient with angina pectoris on exertion associated with discrepancies in laboratory values comprising an increase in quantitative cardiac troponin T (cTnT) and in total and MB creatine kinase (CK) and a negative result for cTnT rapid test. They conclude that the cTnT rapid test failed to diagnose myocardial infarction in this patient. However, we propose another hypothesis: that the patient had no myocardial infarction but only a macro CK in his serum.

Macro CK is an abnormal CK isoenzyme found in approximately 1% of patients tested for CK.² Type 1 macro CK may result from aggregates of monoclonal IgG and is reported to be associated with autoimmune diseases. Type 2 macro CK may be associated with neoplastic diseases. Macro CK may be responsible for an increased plasma concentration of total and MB CK when these parameters are . . . [Full Text of this Article]