Gastrin in blood plasma
Reference values of gastrin concentration in blood plasma in adults - 25-90 pg / ml( ng / l).
Gastrin is formed in the G cells of the antral part of the stomach and is synthesized in small amounts in the mucosa of the small intestine. The main forms of gastrin( G) in the blood plasma are G-34( a large gastrin, with a half-life of 42 min), G-17( a small gastrin, with a half-life of 5 min) and G-14( minigastrin, with a half-life of 5 min).G-17 consists of 17 amino acids and is a mature hormone, form G-34 contains 34 amino acids and is a biologically active precursor of gastrin. The main method for determining the concentration of gastrin in the blood plasma is RIA, which detects both hormones in total in one sample. Gastrin stimulates the secretion of hydrochloric acid. Fluctuations in the concentration of gastrin in the blood are subject to the daily rhythm: the lowest values are noted between 3 and 7 am, the highest - in the daytime or in connection with eating.
The greatest clinical significance of determining the level of gastrin in the blood is for the diagnosis of Zollinger-Ellison syndrome( an increase in the concentration of up to 300-350,000 pg / ml is detected in 93% of patients).An increase in the concentration of gastrin in the blood is possible with pernicious anemia( 130-2300 pg / ml), stomach cancer, atrophic gastritis, CRF.For differential diagnosis of the pathology causing an increase in gastrin in the blood, a sample is used with stimulation with calcium chloride or secretin. Calcium chloride is administered intravenously at a dose of 15 mg / kg in 500 ml of a 0.9% solution of sodium chloride for 4 hours. Blood samples are taken on an empty stomach and 1, 2, 3 and 4 hours after the administration of calcium chloride. In Zollin-Gera-Ellison syndrome, the content of gastrin in blood samples increases more than 450 pg / ml, and in patients with atrophic gastritis and pernicious anemia it decreases [Tiz U., 1986].The criteria for the diagnosis include: the pH of the gastric juice below 3, the concentration of gastrin in the fasting serum above 1000 pg / ml or its increase by more than 200 pg / ml for 15 min after intravenous administration of secretin, or more than 450 pg / ml afteradministration of calcium chloride.
Reducing the concentration of gastrin in the blood is revealed in patients after gastroectomy, with hypothyroidism.