Total creatine kinase and isoenzyme fractions in chronic dialysis patients

We measured total serum creatine kinase (CK) and serum creatine kinase MB fraction (CK-MB) in 53 patients on continuous ambulatory peritoneal dialysis (CAPD) and 52 patients on maintenance hemodialysis (HD), using Scalva UV methodology for CK and electrophoresis for CK-MB. Seven of the 53 CAPD patients (13%) had an elevated total CK, and only one of these 7 patients had an elevated CK-MB greater than 5%. In contrast 22 HD patients (42%) had increased total CK values, and 6 of these 22 HD patients (27%) showed elevated CK-MB isoenzyme greater than 5%. For each sex, blacks had higher mean CK values than whites. Twenty-one out of the 43 HD patients who received intramuscular injections had elevated total CK values and 6 of these 21 patients had elevated CK-MB isoenzyme independent of the timing of injection. The increased frequency of higher total CK values in HD patients appears to be related to race and androgen administration. The modest elevations in CK-MB fraction (5 to 8%) in these patients require careful interpretation.