The Atypical Presentation of Ifosfamide-Induced Renal Tubular Acidosis.

Antineoplastic agents are often associated with a wide range of side effects, caused by either direct toxicity or indirect through their metabolism. Ifosfamide is a cytotoxic, antineoplastic medication that is known to cause a direct tubular injury with an associated normal anion gap metabolic acidosis due to type 1 or type 2 renal tubular acidosis (RTA). The manifestations and approach to its diagnosis have been well established. However, we present a case in which a patient presented with acute symptomatic hypokalemia in the setting of ongoing ifosfamide use for metastatic osteosarcoma but without the typical laboratory findings. The clinical- and laboratory-driven diagnosis of suspected type 3 renal tubular acidosis involving proximal and distal segments is suggested by this case report.