Cardiac effects of therapy with lithium: An enzymatic study

Prophylactic therapy with lithium has been associated with various side effects on different organ systems, but any direct relationship between chronic therapy with lithium and myocardial injury has yet to be firmly established. We evaluated a group of 89 patients being treated with lithium for myocardial injury as suggested by increases in total creatine kinase (CK) and creatine kinase-MB (CK-MB) activity in serum of two of six patients with lithium toxicity who had such increases. Three others with therapeutic lithium concentrations in their serum also showed increased CK and CK-MB activity. Myocardial injury, with subsequent release of CK and CK-MB into the circulation, is not uncommon in patients with lithium toxicity. The duration and the degree of lithium toxicity appear to be important factors affecting release of CK and CK-MB. Patients with therapeutic concentrations of lithium may also be at risk for myocardial injury with release of CK and CK-MB into the serum, especially if on long-term treatment with lithium and if older than 60 years.