Introduction: Nephrogenic diabetes insipidus (DI) is a polyuric and polydipsic syndrome and can have multiple causing factors.
Case description: A 69-year-old woman with bipolar disorder medicated with lithium 400mg for 12 years on a daily basis. The patient was admitted, after psychiatric decompensation, with hypernatremia unresponsive to hypotonic iv fluids. The diagnosis of DI was made with high plasmatic osmolality measurement, low urine osmolality, and high levels of antidiuretic hormone. Full clinical recovery was possible with lithium suspension, hydration, and chlorthalidone.
Discussion: Although frequently used in the past, Lithium (Li) is nowadays rarely used in clinical practice for prolonged treatments because of its potentially devastating side effects. Clinicians must be aware of those side effects in order to prevent organ damage, mainly in patients with severe bipolar disease and precarious response to alternative treatments.