Paraneoplastic Hypoglycemia Secondary to Clear Cell Renal Cell Carcinoma: An Unusual Case with Acute Neurological Presentation

Abstract

Introduction: Non-insulin-mediated hypoglycemia in non-diabetic patients is an uncommon clinical finding and may be associated with extrapancreatic neoplasms, such as IGF-2–secreting tumors. We report a case of severe hypoglycemia in a patient with clear cell Renal Cell Carcinoma (ccRCC).

Case Presentation: A 71-year-old male was admitted after an episode of syncope accompanied by seizures and confusion. Capillary blood glucose was measured at 10 mg/dL, requiring continuous dextrose infusion. Laboratory workup excluded insulinoma and showed elevated C-peptide levels. Abdominal CT revealed a right renal mass, and radical nephrectomy confirmed a pT1b clear cell renal cell carcinoma. Hypoglycemia resolved completely following tumor resection.

Discussion: Non–Islet Cell Tumor Hypoglycemia (NICTH) due to IGF-2 overproduction (“big IGF-2”) is a rare paraneoplastic syndrome typically associated with solid tumors, including renal carcinomas. Diagnosis requires exclusion of alternative causes and demonstration of clinical resolution after tumor removal.

Conclusion: Paraneoplastic hypoglycemia should be suspected in patients with visceral tumors and unexplained hypoglycemia in the absence of hyperinsulinemia. Early recognition may allow for curative surgical treatment.