2018 Volume 67 Issue 1 Pages 113-118
Lithium (Li) is often used as a therapeutic agent for manic depression. Since the therapeutic dose is only slightly different from the toxic one, therapeutic drug monitoring is always necessary. Since Li is metabolized by the kidney, toxic symptoms easily develop in patients with impaired renal function. Here, we report the cases of two patients who were diagnosed as having Li toxicosis after coming to our hospital with loss of consciousness (LOC). Case 1: A thirty-year-old woman took multiple drugs at high doses including 12,800 mg of Li with suicidal intent. The concentration of Li in the blood was 13.2 mEq/L. The patient had renal dysfunction. After receiving continuous hemodialysis (CHD) for 30 hours, the Li concentration decreased to 1.2 mEq/L. Twenty-one hours after the completion of CHD, the Li concentration became 0.8 mEq/L. She was discharged from our hospital without showing signs of relapse. Case 2: In an 80-year-old woman with appetite loss, Li concentration was routinely measured. The administration of 400 mg/day Li maintained Li within the range of therapeutic concentrations. On arrival at our hospital, the concentration of Li increased to 1.8 mEq/L owing to renal dysfunction after dehydration. By fluid therapy, she recovered on the same day. We calculated the total number of patients in whom the Li concentration was measured in our laboratory over the past 17 years and confirmed that the Li concentrations in 19 (40.4%) out of 47 patients with LOS reached the toxic range. It is useful to measure the Li concentration in LOC patients taking Li.
