Iron Metabolism
Hye guys, Its been a while since my last entry. Since you guys already know what is haemopoiesis is all about…so here we go on what is Iron metabolism…you know what iron metabolism happens every day in OUR BODY and its is one of the most IMPORTANT process. Chill chill, Sit back and relax
Actually human iron metabolism is the set of chemical reactions maintaining human homeostasis of iron at both the systemic and cellular level. The control of this necessary but potentially toxic metal is an important part of many aspects of human health and disease.
Thats why our expert haematologists have been interested in systemic iron metabolism because iron is essential for red blood cells, where most of the our body's iron is contained.
How does iron work in our body?
Iron helps red blood cells deliver oxygen from the lungs to cells all over the body. Once the oxygen is delivered, iron then helps red blood cells carry carbon dioxide waste back to the lungs to be exhaled. Iron also plays a role in many important chemical reactions in the body.
So you guys must wonder how our body use up iron is it?
Actually most of the iron in the body is recycled when old red blood cells are taken out of circulation and destroyed, with their iron scavenged by macrophages in the mononuclear phagocyte system, mainly spleen, and returned to the storage pool for re-use. Iron homeostasis is closely regulated via intestinal absorption.
So what is iron good for?
Hemoglobin represents about two-thirds of the body's iron. If you don't have enough iron, your body can't make enough healthy oxygen-carrying red blood cells. A lack of red blood cells is called iron deficiency anemia. Without healthy red blood cells, your body can't get enough oxygen.
How is iron absorbed by our body?
The portion of the small intestine called the duodenum is the chief area where iron absorption takes place. There may be a second minor absorption site near the end of the small intestinal tract. Once iron is absorbed it is carried (transported) by a protein called transferrin.
Here are the steps of iron absorption and storage:
Iron that enters the duodenal cells can follow one of two pathways transport to the blood or storage as mucosal iron.
Fe[2]+ iron destined for the circulation, is transported from the cytoplasm across the basolateral enterocyte membrane by ferriportin.
This process is coupled to the oxidation of Fe[2]+ iron to Fe[3]+ iron, which is carried out by the iron oxidases hephaestin and ceruloplasmin.
Newly absorbed Fe[3]+ iron binds rapidly to the plasma protein transferrin, which delivers iron to red cell progenitors in the marrow.
FERRIPORTIN AND DMT1 ¢ DMT1 and ferriportin are widely distributed in the body and are involved in iron transport in other tissues as well. ¢ DMT1 also mediates the uptake of “functional” iron (derived from endocytosed transferrin) across lysosomal membranes into the cytosol of red cell precursors in the bone marrow,
Ferriportin plays an important role in the release of storage iron from macrophages.
Hepicidine
Iron absorption is regulated by hepcidin, synthesized by liver in response to increases in intrahepatic iron levels.
Hepcidin inhibits iron transfer from the enterocyte to plasma by binding to ferriportin and causing it to be endocytosed and degraded.
As hepcidin levels rise, iron becomes trapped within duodenal cells in the form of mucosal ferritin and is lost as these cells are sloughed.
With low body stores of iron, hepcidin synthesis falls and this in turn facilitates iron absorption.
By inhibiting ferriportin, hepcidin reduces iron uptake from enetrocytes and suppresses iron release from macrophages.
This, is important in the pathogenesis of anemia of chronic diseases.
ROLE OF HEPCIDIN IN DISEASES INVOLVING DISTURBANCES OF IRON METABOLISM.
Anemia of chronic disease is caused in part by inflammatory mediators that increase hepatic hepcidin production. A rare form of microcytic anemia is caused by mutations that disable TMPRSS6, a hepatic transmembrane serine protease that normally suppresses hepcidin production when iron stores are low. Affected patients have high hepcidin levels, resulting in reduced iron absorption and failure to respond to iron therapy. Hepcidin activity is inappropriately low in both primary and secondary hemochromatosis.
CAUSES FOR DIETARY IRON DEFICIENCY
• Infants, who are at high risk due to the very small amounts of iron in milk.
• The impoverished, who can have suboptimal diets for socioeconomic reasons at any age.
• The elderly, who often have restricted diets with little meat because of limited income or poor dentition.
• Teenagers who subsist on “junk” food.
OTHER CAUSES OF IRON DEFICIENCY ARE
impaired absorption is found in sprue, other causes of fat malabsorption (steatorrhea),
chronic diarrhea. Gastrectomy impairs iron absorption by decreasing hydrochloric acid
transit time through the duodenum.
Chronic blood loss is the most common cause of iron deficiency in the Western world.
Iron deficiency in adult men and postmenopausal women must be attributed to gastrointestinal blood loss until proven otherwise.
What is the diagnosis of hemochromatosis?
The blood tests you have may include transferrin saturation (TS), serum ferritin level, and liver function tests. Transferrin is a protein that carries iron in the blood. ... Blood tests alone can't diagnose hemochromatosis. Thus, your doctor may recommend other tests as well. Liver Biopsy.
REFERENCES LINK
1. http://library.med.utah.edu/WebPath/TUTORIAL/IRON/IRON.html
2. https://www.med-ed.virginia.edu/courses/path/innes/nh/iron.cfm
3. http://www.mayoclinic.org/diseases-conditions/iron-deficiency-anemia/symptoms-causes/dxc-20266514