Unrecognised Free Water Loss in a Patient with Lithium-Induced Nephrogenic Diabetes Insipidus Can Cause Acute Kidney Injury and Near Fatal Hypernatremia...

Lithium is the commonest cause of drug induced nephrogenic diabetes insipidus (NDI) [1], a condition in which the patient passes large amounts of dilute urine due to the kidney’s loss of the ability to concentrate the urine in response to anti diuretic hormone (ADH). Affected patients may satisfy their polydipsia and avoid dehydration and hyper natremia if they have access to water, but severe hypernatremia can develop if they become acutely unwell or if oral intake of water is restricted. We report a patient on long -term lithium therapy for bipolar disorder who presented with severe confusion, dysarthria and disorientation, and subsequently developing severe hyper natremia and coma despite intravenous saline infusions. She was intubated and ventilated and successfully treated with initial volume expansion and subsequently with intravenous 5% dextrose in water.