Iatrogenic Aberrations of Serum Enzyme Activity*

1. Three forms of iatrogenic serum enzyme al terat ion are presented, each entailing a different mechanism of action. 2. Recent modifications in creatinine phosphokinase (CPK) assay systems have great ly increased the sensit ivity of this measurement . This increase in sensit ivity has been accompanied by a relative decrease in clinical specificity. In pat ients receiving intramuscular injections of drugs, resort may have to be made to the SGOT, L D H or isoenzymes of L D H . Th e lat ter also appear to be the only common measurements not liable to modification by narcotics injected intra-muscularly in pat ients with biliary t rac t disease. 3. Pos t -va lvulo tomy patients with anginal chest pain cannot be satisfactorily assessed by L D H or L D H isoenzyme assays. C P K and SGOT estimations are the procedures of choice because of their relative insusceptibili ty to act ivi ty changes secondary to hemolysis.