Pancreatic endocrine tumors

Published on 02/03/2015 by admin

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Last modified 02/03/2015

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CHAPTER 53

Pancreatic endocrine tumors

1. What are the pancreatic endocrine tumors?

2. Are pancreatic endocrine tumors usually benign or malignant?

3. Are pancreatic endocrine tumors associated with other endocrine disorders?

4. What are insulinomas?

5. What is Whipple’s triad?

6. What glucose levels are considered to be hypoglycemia?

7. What are the symptoms of hypoglycemia?

8. What evaluation should be done to test for an insulinoma?

Blood samples can be obtained during an episode of witnessed hypoglycemia, or the conditions that provoke the hypoglycemia must be replicated. This is most commonly done with a prolonged fast (supervised 72-hour fast or outpatient 12- to 18-hour fast). For this procedure, patients are allowed to drink calorie-free, caffeine-free beverages only. Blood is drawn every 6 hours until the glucose is less than 60 mg/dL, and then every 1 to 2 hours. Sufficient blood is obtained for measurement of glucose, insulin, C-peptide, proinsulin, and beta-hydroxybutyrate; glucose is measured immediately on all samples, and the other tests are run only on samples for which the glucose is lower than 55 mg/dL. Insulin antibodies are ordered on one sample, and a urine screen is sent for sulfonylureas and meglitinides. The test is stopped when the patient has typical symptoms, when the glucose level is less than 45 mg/dL (or <55 mg/dL if Whipple’s triad was previously demonstrated) or at the end of 72 hours. At the end of the test, glucagon 1 mg is given intravenously, and glucose is measured 10, 20, and 30 minutes later.

9. What are the diagnostic criteria for an insulinoma?

Hypoglycemia with endogenous hyperinsulinemia must be demonstrated to diagnose an insulinoma. Diagnostic criteria are shown in Table 53-1.

TABLE 53-1.

DIAGNOSTIC CRITERIA FOR INSULINOMA: DEMONSTRATION OF HYPOGLYCEMIA WITH ENDOGENOUS HYPERINSULINEMIA

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*Compared with normal controls who developed glucose <60 mg/dL during a 72-hour fast.

Adapted from Cryer PE, Axelrod L, Grossman AB, et al: Evaluation and management of adult hypoglycemic disorders: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 94:709–728, 2009; and KA Placzkowski, A Vella, GB Thompson, et al: Secular trends in the presentation and management of functioning insulinoma at the Mayo Clinic, 1987–2007. J Clin Endocrinol Metab 94:1069–1073, 2009.

10. How can an insulinoma be localized?

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