Nonislet Cell Tumor Hypoglycemia

Nonislet cell tumor hypoglycemia (NICTH) is a rare cause of hypoglycemia. It is characterized by increased glucose utilization by tissues mediated by a tumor resulting in hypoglycemia. NICTH is usually seen in large mesenchymal tumors including tumors involving the GI tract. Here we will discuss a case, its pathophysiology, and recent advances in the management of NICTH. Our patient was diagnosed with poorly differentiated squamous cell carcinoma of esophagus. He continued to be hypoglycemic even after starting continuous tube feeds and D5W. General workup for hypoglycemia was negative and insulin-like growth factor II (IGF II) was in the normal range. Hypoglycemia secondary to “big” IGF II was considered, and patient was started on steroids. His hypoglycemia resolved within a day of treatment with steroids. Initially patient had hypoglycemia unawareness, which he regained after maintaining euglycemia for 48 hours. 1. Introduction NICTH was first described by Nadler and Wolfer in a patient with hepatocellular carcinoma as early as 1929 [1]. In 1988, Daughaday et al. demonstrated that tumor-induced hypoglycemia was associated with abnormal pro-IGF II (“big” IGF II) acting via the insulin receptor [2]. Being a rare disease, the true incidence of NICTH is not known. But it is estimated to be one per million people years [3]. Most common cancers causing NICTH are tumors of the GI tract, lungs, pancreas, adrenal, and ovary. Table 1 [3–5] shows the list of tumors associated with NICTH. Table 1: Tumors associated with NICTH. 2. Case Report A 63-year-old Caucasian male with poorly differentiated squamous cell carcinoma of esophagus diagnosed 45 days ago with metastasis to lung and liver came to emergency room with dizziness. His fingerstick glucose was 27？mg/dL in the emergency room with corresponding plasma glucose of 19？mg/dL despite PEG tube feeding with Pivot 1.5 at 20？mL/hr. Patient was started on D5W at 100？mL/hr and admitted to medicine floor. He denied previous history of diabetes or use of oral hypoglycemic agents and insulin. He was not on steroids prior to admission. On physical examination, vitals were within normal limits. Positive findings included right upper quadrant mass and PEG tube. No leak from PEG tube was appreciated. Patient continued to be hypoglycemic while on D5W and Pivot. During these hypoglycemic episodes, patient denied dizziness, diaphoresis, palpitation, chest pain, tremor, or weakness. Patient was also conscious and fully awake even when his blood glucose was below 30？mg/dL. Patient’s feed was changed to Jevity (1.5？Cal/mL) at