Severe Diabetic Ketoacidosis With Refractory Hypernatremia due to Hypokalemia-Induced Arginine Vasopressin Resistance: A Case Report and Literature Review.

Diabetic ketoacidosis (DKA) is a life-threatening complication of diabetes characterized by hyperglycemia, high-anion-gap metabolic acidosis, and ketonemia. Hypernatremia in DKA is uncommon and typically reflects disproportionate free water loss. Arginine vasopressin resistance (AVP-R), previously known as nephrogenic diabetes insipidus, may occur in the setting of hypokalemia, leading to polyuria, hypotonic urine, and worsening hypernatremia. We report the case of a 14-year-old previously healthy female who presented with new-onset severe DKA complicated by profound acidosis, hyperglycemia, hypokalemia, and hypernatremia. Despite standard DKA management, she developed persistent polyuria and rising serum sodium levels. Urine studies demonstrated dilute urine with inappropriately elevated pH, raising suspicion for hypokalemia-induced AVP-R. Management included aggressive potassium repletion, careful adjustment of intravenous fluids, and adjunctive desmopressin therapy. This approach resulted in normalization of electrolyte abnormalities, resolution of polyuria, and full clinical recovery. This case highlights the importance of recognizing hypokalemia-induced AVP-R as a reversible cause of refractory hypernatremia in DKA and underscores the need for individualized fluid and electrolyte management beyond standard treatment protocols.