I. Definition

Erythropoietin is glikoproteid hormone that is a growth factor with respect to erythropoiesis . Human erythropoietin is a polypeptide consisting of 165 amino acids. It can stimulate alone or with the participation of other cytokines , growth and development of the precursors of erythrocytes in the bone marrow , causing an increase in the number of red blood cells.

90% of erythropoietin in adults is synthesized and secreted by interstitial cortical kidney fibroblasts , in response to a reduced supply of oxygen to the tissues . The remaining 10 % of EPO are synthesized by hepatocytes and Ito- interstitial cells of the liver ( relevant in the fetal and perinatal ) . Erythropoietin secretion is controlled by the level of oxygen saturation of the blood. Under conditions of hypoxia ( lack of oxygen to cells and tissues ) , erythropoietin plasma increases. Hypoxia may be caused by anemia , reduced oxygen - carrying capacity , decreased oxygen saturation of the hemoglobin molecules and the like. There is an assumption that there is a reverse correlation between the serum levels of EPO and the amount of red blood cells.
 

Additional features of EPO nehemopoetichni : can induce vasoconstriction and hypertension associated with that stimulates angiogenesis and proliferation of smooth muscle fibers, may increase the absorption of iron by the inhibition of the hormone hepsidin . Studies have reported that EPO influences neuronal protection in conditions of hypoxia (e.g. stroke , etc.) , improves memory . Administration of EPO may be effective for treating depression.

II. Test method:

 
ELISA " sandwich principle." EPO ELISA assay using two different mouse monoclonal antibodies specifically directed against different regions of the human EPO .
 
III. Content and clinical significance :

Clinical indications for the study of indicators:
 - Diagnosis and differential diagnosis of anemia and polycythemia ;
 - To help predict and monitor the response to treatment with recombinant erythropoietin in patients with anemia ;

Quantification of EPO serum aid in the diagnosis and differential diagnosis of anemia and erythrocytosis .

1. Anemia :
 Aplastic , haemolytic and iron deficiency anemia - the values ​​of EPO were increased ;
 
 Anemia of kidney disease and certain other diseases ( e.g., AIDS), - the values ​​of EPO are low ;

Low , the concentration of EPO may be an early signal of kidney transplant rejection .

EPO can also be used for monitoring of patients with AIDS of AZT- therapy . The increase in EPO in these patients is a signal that anemia in ongoing AZT- therapy due to hypoplasia / aplasia of the red blood cell .

2 . Upon erythrocytosis :
Polycythemia vera (primary erythrocytosis ) is a result of autonomous proliferation of the 3 lines of blood , with prevalence of erythropoiesis . In these cases, values ​​of EPO are low.

Secondary polycythemia ( poliglobulii ) if it is off dehydration (relative erythrocytosis ) is due to the increase in EPO ( secondary stimulation eritopoezata ) due to various reasons :
Individual elevated EPO - in paraneoplastic syndromes ( with hypernephroma , ovarian carcinoma , tumors of the cerebellum and the like . , In these cases, the EPO may be used as a tumor marker ) in polycystic kidney disease , familial erythrocytosis ;
 
Compensatory increase in EPO - in hypoxia (residing at high altitudes , pulmonary disease , heart disease ) , Disability hemoglobin ( congenital methemoglobinemia , carboxyhemoglobin ) medications ;

For diagnostic purposes , the test results should always be assessed in accordance with the patient's history , clinical and other studies .
 
IV. Material for testing : serum

Important requirements for sampling : it is blood clotting retrahirane clot to become 2 - 8 ° C or on ice. Samples coagulated at room temperature can produce lower amounts of EPO . The separated serum after centrifugation was frozen at -15 ° C or lower temperature , and thus is transported , if needed.