Prevalence of macrocreatinkinase type 1 in patients with inflammatory bowel disease

Macro-creatine-kinases are isoenzymes of creatinine-kinases (CK). They have been classified in two types: type 1 (CK bound to an immunoglobulin) and type 2 (an oligomeric mitochondrial CK). CK type 1 has been found in patients with ulcerative colitis (UC) but not in Crohn's disease (CD). However, there are no studies evaluating macro-creatinkinase prevalence in inflammatory bowel disease (IBD). We included 159 consecutive patients (72 UC, 85 CD; 2 indeterminate colitis). Creatin-kinase total activity and isoenzymes activities were determined. Twelve (16.7%) patients with UC and one of the two patients with indeterminate colitis had serum macro-creatinkinase type 1 while no CD patients displayed this macromolecule (P < 0,001). Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratio were calculated for ulcerative colitis versus Crohn's disease diagnosis, being 16.7, 98.9, 92.3, 59, 14.5, and 0.84% respectively. There was no correlation with age, gender, time from diagnosis, associated diseases, concomitant medication or disease activity. In conclusion our data suggests that the presence of macro-CK in IBD favors the diagnosis of ulcerative colitis. Further studies are necessary to understand the significance of this finding in a subset of patients with IBD.