Relevance of macro creatine kinase type 1 and type 2 isoenzymes to laboratory and clinical data.
From 8322 patients for whom creatine kinase (CK; EC 2.7.3.2) isoenzyme analysis was ordered, we identified 136 patients with macro CK isoenzyme in their serum. There were 36 cases with type 1 (prevalence: 0.43%) and 100 cases with type 2 isoenzyme (prevalence: 1.20%). About three-fourths of the patients were ambulatory at the time of testing, and approximately 90% of the first 68 patients identified survived at least 1 year after macro CK was found in their serum. Age and gender did not differ significantly between the two groups. The serum total CK was significantly higher (P < 0.0005), and an increased CK-MB proportion (> 0.05 of total CK) was also significantly more common (P < 0.0005) in patients with macro CK type 1 than in those with type 2. On average, macro CK type 2 accounted for approximately 25% and macro CK type 1 for approximately 10% of the serum total CK activity. Patients with macro CK type 1 most often had myositis, whereas those with macro CK type 2 most commonly had a malignancy. We conclude that the presence of macro CK isoenzymes has a low prognostic value for impending death, but may support the diagnosis of an autoimmune process (type 1) or malignant cell proliferation (type 2).
Clinical Pathology Department, W. G. Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892.
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Lee
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Csako
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Bernhardt
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Elin
D000263:Adenylate Kinase / Q000737:chemistry; D000293:Adolescent; D000328:Adult; D000368:Aged; D000906:Antibodies / Q000494:pharmacology; D003402:Creatine Kinase / Q000037:antagonists & inhibitors / Q000097:blood* / Q000737:chemistry*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007527:Isoenzymes; D046911:Macromolecular Substances; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D009220:Myositis / Q000201:enzymology; D009369:Neoplasms / Q000201:enzymology; D012016:Reference Values
D000906:Antibodies; D007527:Isoenzymes; D046911:Macromolecular Substances; D003402:Creatine Kinase; D000263:Adenylate Kinase