C-peptide suppression test for insulinoma.
During hypoglycemia induced by an infusion of porcine insulin, impaired suppression of endogenous insulin secretion as measured by C-peptide was demonstrated in 11 of 12 patients with insulinoma. During hypoglycemia (plasma glucose less than or equal to 40 mg/dl) the mean C-peptide immunoreactivity (CPR) of normal subjects was less than or equal to 1.2 ng/ml, whereas 11 of 12 insulinoma patients had a mean CPR of larger than or equal to 1.9 ng/ml. One patient showed normal CPR suppression by these criteria but may have shown impaired CPR suppression for glucose less than or equal to 30 mg/dl. Impaired CPR suppression during insulin-induced hypoglycemia may prove to be a useful test for insulinoma.
D007516:Adenoma, Islet Cell / Q000097:blood / Q000378:metabolism*; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D005246:Feedback; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000097:blood / Q000378:metabolism*; D010455:Peptides; D011384:Proinsulin / Q000097:blood; D013997:Time Factors
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D010455:Peptides; D011384:Proinsulin