Non-Islet Cell Tumor Hypoglycemia: A Rare Cause of Hypoglycemia in Pulmonary Sarcomatoid Cancer

Non-islet cell tumor hypoglycemia (NICTH) is a rare paraneoplastic condition caused most commonly by metastatic mesenchymal tumors. A 74-year-old non-diabetic male with an eight-year history of metastatic sarcomatoid lung cancer presented with altered mental status. His previous treatment included a lobectomy and radiation. Laboratory investigations were significant for blood glucose of 28 mg/dL, confirming hypoglycemia. He was hypokalemic, a condition seen in approximately 50% of patients with NICTH, at 2.8 mEq/L of potassium (normal 3.5-5.2 mEq/dL) and his urine toxicology screen was negative. A computed tomography (CT) of the head was negative for any acute events. His tumor burden had progressed as compared to previous CTs. Administration of dextrose resolved his symptoms. Laboratory studies during subsequent hypoglycemic events measured his insulin-like growth factor-I (IGF-I) at 51 ng/mL, insulin-like growth factor-II (IGF-II) at 290 ng/mL, growth hormone (GH) at 0.6 ng/mL, C-peptide at 0.16 ng/mL (low), and insulin levels at <1 uIU/mL. ‘Big’ IGF-II, the gold standard for the diagnosis of NICTH, was not available at our facility. Based on these results, NITCH was diagnosed clinically. NICTH is a rare condition with episodes of recurrent hypoglycemic episodes in the setting of metastatic cancer. Ideal therapy for NICTH is tumor resection or debulking. In cases of inoperable tumors, glucocorticoids or recombinant human growth hormone (rGH) maintain euglycemia, with glucagon rescue in case of an emergency.