Serotonin in serum

Reference values ​​of serotonin concentration in serum in adults - 0,22-2,05 μmol / l( 40-80 mkg / l);in whole blood - 0.281.14 μmol / l( 50-200 ng / ml).

Serotonin( oxytryptamine) is a biogenic amine, mainly contained in platelets. The body constantly circulates up to 10 mg

Fig. Algorithm for diagnosing the type of chronic gastritis

Fig. Algorithm for diagnosing the type of chronic gastritis

serotonin. From 80 to 95% of the total amount of serotonin in the body is synthesized and stored in enterochromaffin cells of the gastrointestinal tract. Serotonin is formed from tryptophan as a result of decarboxylation. In enterochro-muffin GIT cells, most of the serotonin is adsorbed by platelets and enters the bloodstream. In large quantities, this amine is localized in several parts of the brain, it is abundant in the mast cells of the skin, it is found in many internal organs, including various endocrine glands.

Serotonin causes platelet aggregation and polymerization of fibrin molecules, with thrombocytopenia it is able to normalize the retraction of the blood clot. It has a stimulating effect on the smooth muscles of blood vessels, bronchioles, intestines. Provoking an exciting effect on smooth muscles, serotonin narrows bronchioles, causes increased intestinal peristalsis, and having a vasoconstrictive effect on the vascular network of the kidneys, leads to a decrease in diuresis. Insufficiency of serotonin lies at the basis of functional intestinal obstruction. Serotonin of the brain acts depressingly on the function of the reproductive system involving the epiphysis.

The most studied pathway of the metabolism of serotonin is its conversion into 5-hydroxyindoleacetic acid under the action of monoamine-cydase. In this way, 20-52% of serotonin is metabolized in the human body.

Carcinoid syndrome is a rare disease caused by increased secretion of serotonin by a carcinoid, which in more than 95% of cases is located in the digestive tract( vermiform appendage - 45.9%, ileum - 27.9%, rectum - 16.7%), butcan be in the lungs, bladder, etc. Carcinoid develops from argyrophilic cells of intestinal crypts. Along with serotonin, the carcinoid produces histamine, bradykinin and other amines, as well as prostaglandins. All carcinoids are potentially malignant. The risk of malignancy increases as the size of the tumor increases.

The concentration of serotonin in the blood in carcinoid syndrome increases 5-10 times. In healthy people, only 1% of tryptophan is used for the synthesis of serotonin, while in carcinoid patients it is used up to 60%.Increased synthesis of serotonin in a tumor leads to a decrease in the synthesis of nicotinic acid and the development of symptoms specific for PP( pellagra) avitaminosis. In the urine of patients with malignant carcinoid, a large number of products of the metabolism of serotonin - 5-hydroxyindoleacetic and 5-oxyindolylaceturonic acids - are detected. Isolation of 5-hydroxyindoleacetic acid in the urine, exceeding 785 μmol / day( norm - 10,5-36,6 μmol / day), is considered a prognostically unfavorable sign. After a radical surgical removal of the carcinoid, the concentration of serotonin in the blood and the excretion of the products of its metabolism in the urine are normalized. The lack of normalization of the excretion of metabolic products of serotonin indicates a non-surgical operation or the presence of metastases. Some increase in the concentration of serotonin in the blood can be in other diseases of the digestive tract.

The main diseases and conditions in which the concentration of serotonin in the blood can vary are shown in the table.

Table Diseases and conditions in which the serotonin concentration in the blood serum changes

Table Diseases and conditions at which the serotonin concentration inserum

Increased concentration	Decreased concentration
Metastases of abdominal carcinoma	Down syndrome
Medullary thyroid cancer	Untreated phenylketonuria
Dempiesng-syndrome
Acute intestinal obstruction
Cystic fibrosis
IM