Among the various diagnostic criteria for insulinoma, the ratio criteria have been controversial. However, the amended insulin-glucose ratio exhibited excellent diagnostic performance in a recent retrospective cohort study, although it has not yet been validated in other patient cohorts. We examined the diagnostic performance of the current criteria of the Endocrine Society, insulin-glucose ratio, C-peptide-glucose ratio, and amended ratios in terms of differentiating insulinomas.
We reviewed the medical records of patients who underwent evaluation for hypoglycemia from 2000 to 2013. Fourteen patients with histopathologically confirmed insulinoma and 18 patients without clinical evidence of insulinoma were included. The results of a prolonged fast test were analyzed according to the abovementioned criteria.
Fulfilling all three Endocrine Society criteria-plasma levels of glucose (<3.0 mmol/L), insulin (≥8 pmol/L), and C-peptide (≥0.2 nmol/L)-exhibited 100% sensitivity and 89% specificity. Fulfilling the glucose and C-peptide criteria showed 100% sensitivity and 83% specificity, while fulfilling the glucose and insulin criteria showed 100% sensitivity and 72% specificity. Among the ratio criteria, the insulin-glucose ratio [>24.0 (pmol/L)/(mmol/L)] gave the highest area under the receiver operating characteristic curve, with 93% sensitivity and 94% specificity.
Fulfilling the glucose, insulin, and C-peptide criteria of the Endocrine Society guidelines exhibited the best diagnostic performance for insulinoma. Nonetheless, the insulin-glucose ratio may still have a role in the biochemical diagnosis of insulinoma.
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We report a rare case of severe hypoglycemia after sunitinib treatment for pancreatic neuroendocrine carcinoma. We describe the initial clinical presentation, laboratory results, pathologic findings, and managment in a patient with a nonfunctioning pancreatic neuroendocrine carcinoma with liver metastases who developed life threatening hypoglycemia after 2 months of sunitinib therapy. A 46-year-old woman presented to the emergency department with loss of consciousness from hypoglycemia. Serum C-peptide and insulin levels at fasting state revealed that the hypoglycemia resulted from endogenous hyperinsulinemia. She had been diagnosed with nonfunctioning pancreatic neuroendocrine carcinoma based on a biopsy of metastatic cervical lymph node and was being treated with sunitinib, a small molecule tyrosine kinase inhibitor. Immunohistochemical stain of the metastatic liver mass demonstrated that the initially nonfunctioning neuroendocrine carcinoma cells had changed into insulin-producing cells after sunitinib therapy. Transarterial chemoembolization of the liver masses and systemic chemotherapy with streptozotocin/adriamycin relieved the hypoglycemia. A nonfunctioning pancreatic neuroendocrine carcinoma was transformed into an insulin-producing tumor after treatment with sunitinib, causing endogenous hyperinsulinemia and severe hypoglycemia.
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