Diagnose an Insulinoma:
- Diagnosis of insulinoma is established by demonstrating inappropriately high serum insulin concentrations during a spontaneous or induced episode of hypoglycemia
- Ex: 72-hour fast for a patient with fasting hypoglycemia or in the case of the patient with solely postprandial symptoms, the mixed meal test.
- Fasting hypoglycemia – Postprandial hypoglycemia may be a feature or even the sole manifestation of hypoglycemia in some patients. The hypoglycemia in persons with insulinoma is primarily due to reduced hepatic glucose output rather than increased glucose utilization
- Transabdominal ultrasonography is the preferred initial test. The rate of detection by transabdominal ultrasound and triple-phase spiral CT of the pancreas is approximately 70 percent
- Plasma insulin, C-peptide, and proinsulin values are elevated in patients with insulinomas, oral hypoglycemic agent-induced hypoglycemia, and insulin autoimmune hypoglycemia.
- Sulfonylurea or meglitinides are present in the plasma only in oral hypoglycemia agent-induced hypoglycemia.
- The presence of insulin or insulin receptor antibodies can distinguish insulin autoimmune hypoglycemia from insulinoma.