New onset hyperglycemia attributed to renal cell carcinoma.

A 61-year-old male was admitted from the outpatient setting for treatment of severe hyperglycemia. Five months earlier, his hemoglobin A1c had been 5 mmol/mol. At presentation, hemoglobin A1c was 11.3 mmol/mol and he required insulin therapy at discharge. Later magnetic resonance imaging (MRI) identified bilateral renal masses, previously seen on ultrasound during workup for chronic kidney disease, as being suspicious for renal cell carcinoma (RCC). He underwent partial nephrectomy and cryoablation with pathology showing papillary type RCC. Hyperglycemia resolved after resection and insulin therapy was discontinued, requiring only an oral hypoglycemic. Hyperglycemia as a paraneoplastic syndrome related to RCC is rare. The cause of this acute hyperglycemia is not understood, though previously suggested mechanisms include ectopic glucagon production, autoimmune causes and interleukin-6 (IL-6) mediated pathways. Severe, new-onset hyperglycemia in the absence of common causes and with a renal mass on imaging may represent an uncommon paraneoplastic syndrome secondary to RCC.