[Hypernatremia as a rare complication in change from lithium to valproate]

This paper is about a female patient who suffered from bipolar disorders for several decades. Due to a change in medication from lithium to valproic acid by infusion, the patient fell into a coma. Hypernatremia, which had developed unnoticed, was later discovered as the reason. This hypernatremia was due to renal diabetes insipidus stemming from the decades of lithium therapy, with accompanying polydipsia and polyuria, and also to the failure to give enough fluid to the somnolent patient.