A Rare Case of Lithium-induced Partial Nephrogenic Diabetes Insipidus.

Chronic lithium therapy in patients with bipolar disorder and other psychiatric illnesses can lead to a very common side effect of complete or partial nephrogenic diabetes insipidus. After confirmation of hypotonic polyuria, water deprivation test with desmopressin injection is used to make the diagnosis. Incomplete response to desmopressin suggests partial nephrogenic diabetes insipidus. We report a rare case of a 58-year-old patient who presented with hypernatremia and hypotonic polyuria secondary to chronic lithium therapy. She was diagnosed with partial nephrogenic diabetes insipidus secondary to chronic lithium therapy and was treated with amiloride resulting in improvement.