Erythropoietin is a glycosylated protein produced by peritubular cells of kidney. It is essential for normal reticulocyte production.
Stimulus for release is hypoxia.
Recombinant form is available as apoprotein, which is commonly used. Glycosylated form is Darbipoietin Alpha. It has additional 2 carbohydrate chains, which improve biological activity. Its half life is 3 times more and has delayed onset. It is of no value in acute treatment of anemia. Used in supplementation with iron.
Erythropoietin binds to cytokine receptors (belong to JAK-STAT super-family). When bind these receptors, activation of JANUS kinases take place, which in turn lead to activation and phosphorylation of STAT. STAT travels to nucleus and brings about transcription responsible for biological response.
Proliferation & differentiation of erythroid
Erythropoietin binding causes proliferation and differentiation of erythroid cells.
Hypertension, thrombotic complications & allergies
Since erythropoietin increases hemoglobin, hematocrit and reticulocyte count, it can aggravate hypertension and thrombotic events, as well as can cause allergies.
- Chronic Renal Failure
Normally inverse relation is seen between hemoglobin and erythropoietin. When hemoglobin decreases, erythropoietin increases exponentially. In chronic renal failure, this inverse relation is lost. Kidneys are not able to produce erythropoietin normally, thus patients have to be given exogenous erythropoietin.
- Primary bone marrow disorders
Selected patients of anemia due to primary disorders of bone marrow
- Secondary anemias
Secondary anemias, including myeloproliferative myelodisplastic conditions, aplastic anemia, multiple myeloma and different cancers. So given to treat these anemias.
In patients of AIDS, Zidovudine causes anemia.
Patients of phlebotomy are given to accelerate erythropoiesis.
- Anemia of prematurity
In sports, banned by international Olympic committee due to the fact that it increases RBCs, oxygen delivery and performance.