C-peptide suppression test for insulinoma
Service, F.J.; Horwitz, D.L.; Rubenstein, A.H.; Kuzuya, H.; Mako, M.E.; Reynolds, C.; Molnar, G.D.
Journal of Laboratory and Clinical Medicine 90(1): 180-186
1977
ISSN/ISBN: 0022-2143 PMID: 194989 Document Number: 116748
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.