Hypercalcemia-Induced Renal Tubular Acidosis (RTA) in Advanced Gynecologic Cancer: A Diagnostic Challenge

Introduction: Type 1 Renal Tubular Acidosis is an uncommon disorder, particularly in adults that is characterized by an impaired acidification of the distal renal tubule. The etiology and diagnosis could mean a more severe or even yet catastrophic underlying condition. Case Description: A 30 year old female with no prior medical history presented with progressive bilateral leg weakness, back pain, and paresthesias for 1–2 months, resulting in multiple falls. Exam revealed 3 out of 5 lower limb strength, diminished reflexes, and inability to ambulate without assistance. Labs met SIRS criteria and showed normocytic anemia, high anion gap metabolic acidosis with respiratory alkalosis and non-anion gap components, moderate hypokalemia, hypercalcemia, AKI KDIGO stage I, elevated liver enzymes, bilirubin, and lactate. CT imaging revealed a large pelvic mass (likely ovarian vs endometrial), liver and lung metastases, lymphadenopathy, and lytic lesions in the right ilium, sacrum, and L5–S1 vertebrae. She was admitted for IV hydration, antibiotics, PRBC transfusion, and electrolyte correction. AKI improved, but acidosis persisted. Urine pH was 5.5 with a positive urine anion gap, consistent with distal RTA. Hypercalcemia was attributed to malignancy and treated with bisphosphonates and Sodium Citrate with initial response. Despite persistent leukocytosis, cultures were negative and antibiotics were discontinued. GI workup was negative. Liver biopsy confirmed metastatic undifferentiated adenocarcinoma of gynecologic origin. Head CT was normal; MRI was not performed given uncompliance due to pain. Her disease progressed to ARDS, multiorgan failure, and death despite aggressive multidisciplinary care. Discussion: This case illustrates the association between an aggressive gynecologic cancer in a young individual and its renal complications. In this scenario, the patient’s advanced gynecologic neoplasm led to severe hypercalcemia, which in turn caused Type 1 Renal Tubular Acidosis. Early recognition of this metabolic disturbance can be crucial, allowing for targeted interventions that may not only facilitate earlier diagnosis of the underlying malignancy but also improve quality of life and potentially extend survival in affected patients.