Abstract: Summary1. Three forms of iatrogenic serum enzyme alteration are presented, each entailing a different mechanism of action.2. Recent modifications in creatinine phosphokinase (CPK) assay systems have greatly increased the sensitivity of this measurement. This increase in sensitivity has been accompanied by a relative decrease in clinical specificity. In patients receiving intramuscular injections of drugs, resort may have to be made to the SGOT, LDH or isoenzymes of LDH. The latter also appear to be the only common measurements not liable to modification by narcotics injected intra-muscularly in patients with biliary tract disease.3. Post-valvulotomy patients with anginal chest pain cannot be satisfactorily assessed by LDH or LDH isoenzyme assays. CPK and SGOT estimations are the procedures of choice because of their relative insusceptibility to activity changes secondary to hemolysis.
