Glucagon in blood plasma

Reference values ​​of glucagon concentration in blood plasma in adults - 20-100 pg / ml( RIA).

Glucagon is a polypeptide consisting of 29 amino acid residues. It has a short half-life( several minutes) and is a functional insulin antagonist. Glucagon predominantly form a-cells of the pancreas, duodenum, however, secretion of ectopic cells in the bronchi and kidneys is possible. The hormone affects the carbohydrate and lipid metabolism in peripheral tissues. In diabetes mellitus, the combined effect of these hormones is manifested by the fact that insulin deficiency is accompanied by an excess of glucagon, which, in fact, causes hyperglycemia. This is especially well demonstrated by the example of treatment of type 1 diabetes, that is, absolute insulin deficiency. In this case, hyperglycemia and metabolic acidosis develop very rapidly, which can be prevented by prescribing somatostatin, inhibiting glucagon synthesis and secretion. After this, even with complete absence of insulin, hyperglycemia does not exceed 9 mmol / l.

Along with somatostatin, the secretion of glucagon suppresses glucose, amino acids, fatty acids and ketone bodies.

A significant increase in the concentration of glucagon in the blood is a sign of glucagon - a tumor of a-cells of the islets of Langerhans. Glucago-noma is 1-7% of all islet-cell tumors of the pancreas;more often localized in her body or tail. Diagnosis of the disease is based on the detection in the blood plasma of a very high concentration of glucagon - above 500 pg / ml( can be in the range of 300-9000 pg / ml).Diagnostic value have hypocholesterolemia and hypoalbuminemia, which are detected in practically all patients. Additional information can be given by the test of oppression of glucagon secretion after loading by glucose. At the patient after night fasting, blood from the vein is initially taken to determine the concentration of glucose and glucagon. After this, the patient takes orally glucose in a dose of 1.75 g / kg. Repeated blood for the study is taken after 30, 60 and 120 minutes. Normally, at the peak glucose concentration in the blood, the concentration of glucagon is reduced to 15-50 pg / ml. In patients with glucagonoma, there is no decrease in the level of glucagon in the blood( negative test).The absence of oppression of glucagon secretion during the test is also possible in patients after gastro-ectomy and diabetes mellitus.

The concentration of glucagon in the blood plasma may increase in diabetes mellitus, pheochromocytoma, liver cirrhosis, Illness-to-Cushing's disease and syndrome, renal failure, pancreatitis, pancreatic injury, familial hyperglucagonemia. Nevertheless, the increase in its content is several times higher than normal, noted only with glucagon-secreting tumors.

A low concentration of glucagon in the blood can reflect a general decrease in pancreatic mass caused by inflammation, swelling, or pancreatectomy.