We report a case of a patient with spindle cell sarcoma of the left thigh, who was treated with combined doxorubicin-Ifosfamide and developed severe hypernatremia and polyuria, alongside findings of acute kidney injury and Fanconi syndrome. Ifosfamide was thought to be the main culprit in her development of arginine vasopressin resistance, and the patient responded favorably to supraphysiological doses of desmopressin (DDAVP). Here, AVP is linked to Hypernatremia.