C-peptide
C-peptide is formed in the islets of Langerhans, specifically the beta cells of the pancreas during insulin production. Since insulin and C-peptide are secreted into the bloodstream in near equal amounts, measuring C-peptide levels provides a reliable indication of blood insulin levels. The C-peptide test is also used to assess the secretory function of the beta cells, and to identify individuals who may be injecting insulin for nontherapeutic reasons.
C-peptide levels are reported as nanogram per milliliter (ng/mL).
The C-peptide test is particularly helpful in measuring blood insulin
levels in diabetic patients who have developed insulin antibodies as a result of being treated with pork or bovine insulin. C-peptide is not affected by the presence of insulin antibodies.
Normal Range
0.78-1.89 ng/rnL
Variations from Normal. Increased C-peptide levels are associated with insulinoma, a benign tumor of the beta cells of the pancreas that causes the excessive secretion of insulin. Since most C-peptide is degraded in the kidney, renal failure results in elevated C-peptide levels.
Decreased C-peptide levels are associated with a radical pancreatectomy and diabetes mellitus. Fictitious hypoglycemia, hypoglycemia caused by secretive injection of insulin, can be identified via decreased levels of Cpeptide.
Interfering Circumstances. Obesity and oral hypoglycemic medications or agents may alter C-peptide test results .
Glucagon
Glucagon a hormone secreted by pancreatic alpha cells, assists in the maintenance of blood glucose levels. When blood glucose levels decrease, glucagon stimulates the conversion of glycogen into glucose, which results in an increase in blood glucose . Glycogen, the stored form of glucose, is found primarily in the liver. Measuring plasma glucagon levels assists in diagnosing pancreatic conditions and disorders. Glucagon levels are reported as picogram per milliliter (pg/mL).
Normal Range
50-200 pg/mL
Variations from Normal. Glucagon levels increase in the presence of acute pancreatitis, diabetes mellitus, severe diabetic ketoacidosis, and glucagonoma, a pancreatic alpha cell tumor. Since glucagon may be metabolized by the kidneys, chronic renal failure or kidney transplant rejection has the potential to cause increased glucagon levels . Decreased glucagon levels are associated with chronic pancreatitis, loss of pancreatic tissue, and idiopathic glucagon deficiency.
Interfering Circumstances . Lifestyle circumstances that may alter glucagon test results include prolonged fasting or moderate to heavy exercise.
Therapeutic interventions that alter glucagon test results consist of radioactive scans within forty-eight hours of testing; drugs such as insulin
Insulin and glucocorticoids that may increase glucagon levels; and drugs such as secretin and propranolol that may decrease glucagon levels.
