False increased CK-MB value after cryoablation of the prostate without myocardial infarct

The authors report on a profound increase in creatine kinase isoenzyme MB (CK-MB) activity in three patients following uneventful cryoablation of the prostate under general anaesthesia: Just after the arrival at the recovery room CK-MB levels were 321 U/l, 245 U/l and 433 U/l, respectively. Other clinical investigations as well as additional laboratory tests ruled out myocardial infarction in all three patients. Electrophoresis of the CK-isoenzymes revealed an increase in CK-BB activity and an increase in atypical CK-BB as a cause of these findings. The presence of these isoenzymes leading to interferences with the antibody commonly used in CK-MB assays could explain the determination of a false positive CK-MB elevation in the three patients. Moreover, it is shown that this method of CK-MB activity determination may result in CK-MB levels higher than 100% of the whole CK activity. In addition, it is discussed that in patients suffering from prostatic carcinoma or other malignoma, "non-CK-M elevations" may occur. Therefore, the authors conclude that after cryoablation of the prostate additional tests like troponin T test and 12 channel ECG are required to rule out suspected myocardial infarction.