[A water intoxication patient who showed remarkable ST depression and suspected ischemic heart disease]

A 63 year old female, who was admitted to a psychiatric hospital for schizophrenia, was referred to our emergency room because of sudden loss of consciousness and convulsions. On arrival, she was drowsy and hypoxemic. Her chest X-ray showed cardiomegaly with pulmonary edema. ECG showed marked ST depression in precordial leads and serum chemistry revealed marked elevation of CPK, GOT and LDH along with hyponatremia and hypochloremia. She was immediately admitted to CCU on suspicion of acute non-transmural myocardial infarction complicated with congestive heart failure. After fluid restriction and intravenous infusion of dopamine she passed large amount of urine, and her consciousness level, electrolyte imbalance and ECG change, improved gradually. Although serum CPK level increased as high as 32,307 IU/ml, there were no signs of left ventricular asynergy on UCG and CPK isozyme analysis performed later revealed more than 99% of serum cCPK was MM-type. We concluded that water intoxication was the cause of the ECG change and the elevated serum CPK, GOT and LDH levels. There are few reports on elevated CPK level in association with water intoxication, in which rhabdomyolysis is speculated as the cause of CPK elevation. But there is no report on ECG change complicated with water intoxication. In our case, electrolyte imbalance caused by water intoxication seemed to play a major role in ST depression and QT prolongation. Although water intoxication is a rare disorder in the general population, it is not infrequent among patients with psychiatric diseases. Care must be taken when such patients present ECG change and serum enzyme elevation mimicking ischemic heart disease.