Red blood cells production

Aplastic anemia—anemia due to deficient red blood cell production in the bone marrow... 

Additionally, with chronic hypoxia, normal hemoglobin and hematocrit values may represent relative anemia.12 Increased red blood cell production is a physiologic response to hypoxia however, this response may be blunted in CF and may result in symptoms of anemia despite normal lab values. Abnormal bleeding may also be observed as a result of vitamin K malabsorption or antibiotic-associated depletion of gastrointestinal flora and vitamin K synthesis. 

Iron supplementation resolves anemia by replacing iron stores in the body that are necessary for red blood cell production and maturation. If treated properly, a response (via the presence of reticulocytosis) should be seen in 7 to 10 days, and hemoglobin values should rise by about 1 g/dL (10 g/L or 0.62 mmol/L) per week. Patients should be reassessed if hemoglobin does not increase by 2 g/dL (20 g/L or 1.24 mmol/L) in 3 weeks. 

Studies have shown that in patients with chemotherapy-related anemia, therapy with erythropoietin products (epoetin-alfa and darbepoetin) can increase hemoglobin, decrease transfusion requirements, and improve quality of life.12 Epoetin is recombinant human erythropoietin, and darbepoetin is structurally similar to endogenous erythropoietin. Both bind to the same receptor to stimulate red blood cell production. Darbepoetin differs from epoetin in that it is a glycosylated form and exhibits a longer half-life in the body. The half-lives of a single subcutaneous injection of epoetin or darbepoetin in patients are roughly 27 and 43 hours, respectively. 

Anemia of chronic kidney disease A decline in red blood cell production caused by a decrease in erythropoietin production by the progenitor cells of the kidney. As kidney function declines in chronic kidney disease, erythropoietin production also declines, resulting in decreased red blood cell production. Other contributing factors include iron deficiency and decreased red blood cell lifespan, caused by uremia. 

Erythropoiesis-stimulating agents Agents developed by recombinant DNA technology that have the same biologic activity as endogenous erythropoietin to stimulate erythropoiesis (red blood cell production) in the bone marrow. 

Erythropoietin A hormone primarily produced by the progenitor cells of the kidney that stimulates red blood cell production in the bone marrow. Lack of this hormone leads to anemia. 

Intrinsic factor is produced by the parietal cells. Within the stomach, it combines with vitamin Bu to form a complex necessary for absorption of this vitamin in the ileum of the small intestine. Vitamin B12 is an essential factor in the formation of red blood cells. Individuals unable to produce intrinsic factor cannot absorb vitamin B12 and red blood cell production is impaired. This condition, referred to as Pernicious anemia, occurs as a result of an autoimmune disorder involving destruction of parietal cells. 

Although the kidneys are not considered endocrine glands per se, they are involved in hormone production. Erythropoietin is a peptide hormone that stimulates red blood cell production in bone marrow. Its primary source is the kidneys. Erythropoietin is secreted in response to renal hypoxia. Chronic renal disease may impair the secretion of erythropoietin, leading to development of anemia. The kidneys also produce enzymes. The enzyme renin is part of the renin-angiotensin-aldosterone system. As will be discussed, these substances play an important role in the regulation of plasma volume and therefore blood pressure. Other renal enzymes are needed for the conversion of vitamin D into its active form, 1,25-d i hyd ro xyv itamin D3, which is involved with calcium balance. 

Compounds that strongly chelate iron have been known for many years to stabilize HIF-la as well as upregulate proteins involved in red blood cell production erythropoietin (EPO), angiogenesis, vascular endothelial growth factor (VEGF), and iron transport. Some, but not all, of the pharmacological actions of iron chelators are produced by inhibition of PHD enzymes resulting in elevation of cellular HIF content. The action of selected iron chelators as they relate to PHD inhibition are briefly summarized here. 

Erythropoietin -hormonal stimulant of red blood cell production —erythrocytosis (with excessive dosage) -flushing... 

Biomedical research continues to broaden our understanding of the molecular mechanisms underlining both health and disease. Research undertaken since the 1950s has pinpointed a host of proteins produced naturally in the body that have obvious therapeutic applications. Examples include the interferons and interleukins (which regulate the immune response), growth factors, such as erythropoietin (EPO which stimulates red blood cell production), and neurotrophic factors (which regulate the development and maintenance of neural tissue). 

EPO (human) 1 165 36 000 Hormone that stimulates red blood cell production... 

The most popular bioassay of EPO involves a mouse-based bioassay (EPO stimulates red blood cell production, making it useful in the treatment of certain forms of anaemia Chapter 10). Basically, the EPO-containing sample is administered to mice along with radioactive iron (57Fe). Subsequent measurement of the rate of incorporation of radioactivity into proliferating red blood cells is undertaken. (The greater the stimulation of red blood cell proliferation, the more iron taken up for haemoglobin synthesis.)... 

Pharmacology Erythropoietin is a glycoprotein that stimulates red blood cell production. It is produced in the kidney and stimulates the division and differentiation of erythroid progenitors in bone marrow. Hypoxia and anemia generally increase the production of erythropoietin, which in turn stimulates erythropoiesis. In patients with CRF, erythropoietin production is impaired this deficiency is the primary cause of their anemia. Epoetin alfa stimulates erythropoiesis in anemic patients on dialysis and those who do not require regular dialysis. 

Pyridoxine (vitamin Bg, 18) (Fig. 13) assists in the balancing of sodium and potassium as well as promoting red blood cell production. A lack of pyridoxine can cause anemia, nerve damage, seizures, skin problems, and sores in the mouth. It is required for the production of the monoamine neurotransmitters serotonin, dopamine, norepinephrine, and epinephrine, as it is the precursor to pyridoxal phosphate, which is the cofactor for the aromatic amino acid decarboxylase enzyme. 

Although the major physiological role of EPO is certainly to promote red blood cell production, EPO mRNA has also been detected in bone marrow macrophages, as well as some multipotential haemopoietic stem cells. Although the physiological relevance is unclear, it is possible that EPO produced by such sources may play a localized paracrine (or autocrine) role in promoting erythroid differentiation. 

Cyanocobalamin, or vitamin B12, is in small amounts required for red blood cell production and for the formation of nucleoproteins and proteins. It is also needed for the proper functioning of the nervous system. Folic acid supplements can correct the anemia associated with vitamin B12 deflciency. Unfortunately, folic acid will not correct changes in the nervous system that result from vitamin B12 deficiency. Vitamin B12 is only found in animal sources such as liver and other organs. Some vitamin B12 is obtained from fish, eggs and milk. Folic acid and cyanocobalamin have been discussed in more detail in Chapter 22. 

A. Approximately 5% of patients taking lithium over the long term develop hypothyroidism, and thyroid status should be followed as routine care for these patients. Mr. Smith s symptoms are classic for hypothyroidism. Impairment in glucose metabolism, hepatic function, red blood cell production, and prolactin secretion are not typical complications of lithium therapy. 

A. General description Erythropoietin is a glycoprotein normally produced in the kidneys and is responsible for the stimulation of red blood cell production. Epoetin alfa is derived via recombinant DNA techniques by mammalian cells after the insertion of the human erythropoietin gene its amino-acid sequence is identical to that of endogenous erythropoietin. Epoetin alfa... 

Anemia. Testosterone and similar compounds are potent stimulators of erythropoietin synthesis from the kidneys and other tissues.109 Erythropoietin, in turn, stimulates production of red blood cell synthesis in bone marrow. Human erythropoietin, however, can now be synthesized using recombinant DNA techniques. Hence, various types of anemia that occur secondary to renal disease, cancer chemotherapy, and so forth are usually treated directly with recombinant erythropoietin.109 Nonetheless, androgens may be used as an adjunct to erythropoietin and other drugs to stimulate red blood cell production in certain patients with severe or recalcitrant anemia.10... 

The cytokine subfamily 1 includes erythropoietin (EPO) (that increases red blood cell production and has accordingly been involved in sports drug abuse), granulocyte colony stimulating factor (G-GSF) (that stimulates leucocyte differentiation), GH (used clinically for growth impairment due to GH deficiency), prolactin (PRL) (that promotes milk production), IL-4 and IL-7. The members of this family act via homodimeric receptors. The leucocyte-derived cytokines of this group variously modulate haematopoiesis and immune responses. 

Slowing of red blood cell production, lower sperm production Anemia, colic, seizure, brain damage, decreased longevity Convulsions, permanent brain damage, death... 

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