A Case of Non-Islet Cell Tumor Hypoglycemia

Presentation Number: MON 604
Date of Presentation: April 3rd, 2017

Thomas Gallagher* and Shyam Narayana
Penn State Hershey Medical Center, Hershey, PA

Abstract

Background: Non-islet cell tumor hypoglycemia (NICTH) is a rare cause of tumor induced hypoglycemia. Other causes of tumor induced hypoglycemia include tumor secretion of insulin and other hormones, such as IGF-2, IGF-1, GLP-1, somatostatin, insulin receptor antibodies and tumor infiltration of the liver. NICTH is most commonly driven by “big”, or incompletely processed IGF-2, which cannot attach to binding proteins leading to hypoglycemia. The most common tumors associated include fibrous tumors, hepatocellular carcinoma, sarcoma, and mesothelioma.

Clinical Case: A 69 year old man was found unresponsive and transported to a local hospital for evaluation. He was found hypoglycemic in the field and was transferred to our institution for persistent hypoglycemia despite dextrose containing fluids and injections. He had a history of DM-2 treated only with metformin which had been gradually weaned off due to normoglycemia and occasional hypoglycemia. He was evaluated two years earlier for a lung mass that was discovered incidentally on imaging. Biopsy of the mass at that time was inconclusive.

The patient was admitted and blood glucose levels were monitored. Liver, thyroid, kidney function, and morning cortisol were normal. Biochemical evaluation for insulin induced hypoglycemia was negative: (blood glucose 54 mg/dl, insulin <1 µU/ml (n < 3 µU/ml), C-peptide 0.37 ng/ml (n < 0.6 ng/ml), proinsulin <5.0 pmol/L (n < 5 pmol/L), β-Hydroxybutyric acid 0.1 mmol/L (n < 0.4 mmol/L), oral hypoglycemic screen negative, Insulin Antibody 0.00). Glucagon administration resulted in a 33 mg/dl increase in blood glucose.

In the setting of a history of lung mass and non-insulin mediated hypoglycemia, NICTH was suspected. Given the severity and persistence of hypoglycemia despite intravenous dextrose treatments, the patient was started on prednisone 30 mg daily. Additional blood work showed: IGF-1 37 ng/ml (n 71-290 ng/ml), IGF-2 217 ng/ml (n 267-616 ng/ml), IGFBP-3 2.0 mg/L (n 3-6.6 mg/L), IGF-2:IGF:1 5.86 (n < 3). CT guided biopsy during the hospital stay confirmed solitary fibrous tumor.

Hypoglycemia quickly resolved with prednisone and the intravenous dextrose was discontinued. The patient eventually underwent resection of the lung mass and was tapered off of prednisone with resolution of hypoglycemia.

Conclusion: NICTH should be considered in patients with hypoglycemia who have coexisting tumors or non-insulin mediated hypoglycemia. Complete surgical resection is curative and subtotal debulking can palliate hypoglycemia. First line treatment is targeted at the underlying tumor, but medical treatment, including corticosteroids, growth hormone, and glucagon, is considered as a bridge to definite treatment or to control hypoglycemia. Octreotide and diazoxide have not been effective in cases of NICTH.

 

Nothing to Disclose: TG, SN