[Elevated serum lithium concentration due to switch from parenteral nutrition alone to parenteral with enteral nutrition].

We report a patient with elevated serum lithium concentration caused by switching from parenteral nutrition alone to parenteral with enteral nutrition. A 73-year-old female inpatient was treated with lithium carbonate 600 mg/d for manic episodes of bipolar disorder. Her serum lithium level was maintained at 0.57-0.79 mEq/L. She was administered total parenteral nutrition owing to difficulty in oral intake. Her diet contained 4.8-5.8 g/d of sodium chloride. After this, parenteral with enteral nutrition was initiated. The total sodium chloride intake decreased from 6.3 to 3.0-4.0 g/d following this change. On day 15 after initiation of parenteral with enteral nutrition, her serum lithium level increased to 1.17 mEq/L, which is closer to the upper therapeutic range limit. Therefore enteral nutrition was stopped immediately, and an electrolyte solution was administered instead of enteral nutrition. An antibiotic agent was also simultaneously administered because of infection. The total amount of sodium chloride administered was increased to 7.0 g/d during this treatment. Four days after treatment, the serum lithium level returned to 0.57 mEq/L. This case suggests that administration of appropriate sodium chloride nutrition is important during treatment with lithium carbonate, because disposition of lithium ion is paralleled to that of sodium.