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Nonautonomous function of a pancreatic insulinoma
The Journal of Clinical Endocrinology and Metabolism
|December 1, 1976
Summary
This case study highlights a 56-year-old woman diagnosed with hypoglycemia. Diagnostic stimulation tests, particularly with tolbutamide, proved more effective than suppression tests in identifying a pancreatic beta cell adenoma.
Area of Science:
- Endocrinology
- Oncology
- Pathology
Background:
- Hypoglycemia diagnosis can be challenging, especially when fasting glucose levels are not critically low.
- Distinguishing between endogenous hyperinsulinism and other causes of hypoglycemia requires careful diagnostic evaluation.
Observation:
- A 56-year-old woman presented with symptoms suggestive of hypoglycemia, including weakness, visual blurring, and sweating.
- Diagnostic studies revealed exaggerated insulin responses to oral glucose and intravenous tolbutamide, accompanied by symptomatic hypoglycemia.
- Elevated basal proinsulin levels (49%) were noted, but a 72-hour fast did not induce hypoglycemia, and exogenous insulin suppressed C-peptide levels normally.
Findings:
- Stimulation tests with oral glucose and intravenous tolbutamide were crucial in diagnosing the patient's condition.
- Surgical exploration revealed a pancreatic beta cell adenoma, confirming the cause of hyperinsulinism.
Implications:
- This case underscores the utility of specific stimulation tests in diagnosing rare cases of hypoglycemia due to pancreatic tumors.
- The findings emphasize that in certain clinical scenarios, stimulation tests may offer greater diagnostic value than suppression tests for hyperinsulinism.