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Erythropoietin (/ ɪ ˌ r ɪ θ r oʊ ˈ p ɔɪ. ɪ t ɪ n,-r ə-,-p ɔɪ ˈ ɛ t ɪ n,-ˈ iː t ɪ n /; [1] [2] [3] EPO), also known as erythropoetin, haematopoietin, or haemopoietin, is a glycoprotein cytokine secreted mainly by the kidneys in response to cellular hypoxia; it stimulates red blood cell production (erythropoiesis) in the bone marrow.
Erythropoietin is produced in the kidney and liver in response to low oxygen levels. In addition, erythropoietin is bound by circulating red blood cells; low circulating numbers lead to a relatively high level of unbound erythropoietin, which stimulates production in the bone marrow.
[2] [3] They are located on the left and right in the retroperitoneal space, and in adult humans are about 12 centimetres (4 + 1 ⁄ 2 inches) in length. [4] [5] They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder.
Erythropoietin is released in response to hypoxia (low levels of oxygen at tissue level) in the renal circulation. It stimulates erythropoiesis (production of red blood cells) in the bone marrow . Calcitriol , the activated form of vitamin D , promotes intestinal absorption of calcium and the renal reabsorption of phosphate .
ESAs are used to maintain hemoglobin at the lowest level that both minimizes transfusions and best meets a person's needs. [8] Medical speciality professional organizations do not recommend the use of ESAs in people with chronic kidney disease (CKD) who have hemoglobin levels greater than 10 g/dL and do not have anemia symptoms.
One of the measures of kidney function is the glomerular filtration rate (GFR). Other tests that can assess the function of the kidneys include assessment of electrolyte levels such as potassium and phosphate, assessment of acid-base status by the measurement of bicarbonate levels from a vein, and assessment of the full blood count for anaemia.
The normal range of GFR, adjusted for body surface area, is 100–130 average 125 mL/min/1.73m 2 in men and 90–120 ml/min/1.73m 2 in women younger than the age of 40. In children, GFR measured by inulin clearance is 110 mL/min/1.73 m 2 until 2 years of age in both sexes, and then it progressively decreases.
They resemble smooth muscle cells and play a role in renal autoregulation of blood flow to the kidney and regulation of systemic blood pressure through the renin–angiotensin system. Extraglomerular mesangial cells are part of the juxtaglomerular apparatus , along with the macula densa cells of the distal convoluted tubule and the ...