Trace element : Iron

IRON
IRON REQUIREMENT
  • Normal iron requirement in an adult female is 21 mg/day.
  • In pregnancy, iron requirement is 35 mg/day.
SOURCES OF IRON
There are two major forms of iron.
  1. maem-iron
  • Better absorbed
  • Less important source of iron in Indian diet.
  • Sources are Animal origin: Liver, meat, poultry and fish
  • Red meat is the richest source of iron.
2. Non-haem iron
  • Poorly absorbed but is the important source of iron in the diet of a large majority of Indian people.
  • Sources are Vegetable origin, i..e, cereals, green leafy vegetables, Leugumes, nuts, oilseeds, jaggery and dried fruits.
  1. Milk is not a good dietary source of iron.Among the pulses , Soyabean has the highest content of iron .
  • Cow milk has slightly more amount of iron than breast milk. However, bioavailability of iron of breast milk is much greater than cow milk.
  • Poor man's iron source is iron.
ABSORPTION,TRANSPORT AND STORAGE OF IRON
  • . Iron is absorbed from upper small intestine mainly duodenum.
  • In diet iron occurs in two forms, haeme iron and inorganic (non-haeme) iron.
  • Haem iron is better absorbed than inorganic iron, but the major fraction of diet is inorganic iron.
  • Inorganic iron is mostly in ferric form; needs to be reduced to ferrous form because iron is absorbed in ferrous form.
  • After absorption ferrous form is once again oxidized to ferric form inside enterocytes.
  • No more than a trace of iron is absorbed in the stomach, but the gastric secretions dissolve the iron and permit it to form soluble complexes with ascorbic acid and other substances that aid its reduction to the Fe2+ form. The importance of this function in humans is indicated by the fact that iron deficiency anemia is a troublesome and relatively frequent complication of partial gastrectomy.
  • Increased iron absorption is seen in: Iron deficiency anemia, pregnancy, hypoxia, acidic pH of stomach, ferrous iron salts,ascorbic acid
  • When there is iron deficiency, absorption increases.
  • This regulation is mediated by "iron metabolism regulatory hormone", i.e., hepcidin that inhibit iron absorption.
  • Hepacidin also decreases release of iron from storage sites.
  • Factors which decreases the bio-availability of iron is presence of phytates, oxalates, carbonates, phosphates, milk,eggs, tea and dietary fiber.
  • Iron is transported is blood in combination with a glycoprotein transferrin..
  • Iron is stored as ferritin (major storage form) or haemosiderin.
  • Ferritin is a complex of iron and apoferritin (iron + apoferritin ferritin).
  • In normal individuals transferrin is about 33% saturated with iron, yielding serum iron levels that average 120 g/dl in men and 100 g/dl in women. Thus the total iron binding capacity of serum is in the range of 300 to 350 g/dl (30-35 mg/litre).
IRON DEFICIENCY ANEMIA
  • Hypochromic Microcytic Anemia
Causes of iron deficiency anemia:
  • Diet
  • Hemorrhage
  • Malabsorption of iron
  • Prolonged achlorhydria may produce iron deficiency because acidic conditions are required to release ferric iron from food.
  • Extensive surgical removal of the proximal small bowel or chronic diseases, such as untreated sprue or celiac syndrome, can diminish iron absorption.
  • Increased demand: pregnancy, lactation and growth periods.
  • Parasitic infection: most comonly by Ankylostoma Duodenale.
Clinical features:
  • Features diagnostic of IDA: Decreased serum ferritin, increased TIBC
  • Earliest sign of IDA: Decrease in serum ferritin
  • Most sensitive and specific test for diagnosing IDA: Serum ferritin levels
  • Hypochromia may be preceded by microcytosis
  • Best test to detect iron deficiency in community is Serum Ferritin
  • . Mentzer index more than 13 suggests a diagnosis of Iron deficiency Anemia.
  • The blood index which reflects iron deficiency more accurately is MCHC
  • Management:
  • Elemental iron supplementation in Iron deficiency anemia is 100-150 mg.
Parenteral iron preparation :
  • Total parenteral iron requirement can be calculated by : 4.3 x Body weight (kg) x Hb deficit (g/dl)
  1. Iron dextran :
  • It can be given either iv or im
  • It binds to transferrin.
  • The risk of anaphylaxis is maximally associated with high molecular weight dextran
  • Indications of parenteral iron supplementation
  • Inability to tolerate oral iron
  • Excessive continuing blood loss
  • Inflammatory bowel disease
  • Chronic kidney disease
  • Cancer patients
  • Heart failurer.ng iron :
  • Rise in Reticulocyte count occurs by the second or third day. This is followed by elevation of haemoglobin levels. Body iron stores are repleted after correction of haemoglobin levels.
  • First change of improvement noted after iron therapy is initiated is decreased irritability.
HEMOCHROMATOSIS
  • Hemochromatosis is characterized by the excessive accumulation of body iron, most of which is deposited in parenchymal organs such as liver and pancreas.
  • In hemochromatosis, hypogonadism is caused by impairment of hypothalamic pituitary function and not due to deposition of Iron in the Testis.
IRON POISONING
  • Ingestion of a number of ferrous sulphate tablets may cause acute iron poisoning.
  • Clinical features : Severe vomiting ,Diarrhea ,GI bleeding ,There may be severe shock, hepatic & renal failure
  • Antidotes:Desferrioxamine is given parenterally (IM or IV), whereas deferiprone and deferasirox are used orally.
Exam Question
  • Bone marrow iron is increased in Thalassemia; Anemia in chronic disease.
  • The normal total iron binding capacity is 30-35 mg/litre.
  • The blood indices which reflects iron deficiency more accurately is MCHC.
  • Raised iron content is not found in testis in Hemochromatosis 
  • Antidotes for acute iron poisoning :Desferioxamine.
  • Iron is absorbed actively in the Duodenum.
  • The iron preparation that can be given intravenously is Iron Dextran.
  • The formula for parenteral iron therapy? 4.4 body weight (kg) Hb deficit (g/dl).
  • Vitamin C increases absorption of oral iron.
  • Oral iron chelating agent(s) is/are Deferiprone, Deferasirox.
  • Iron supplementation in a healthy term breast fed baby should be started at the age of 6 months.
  • Serum ferritin depletes first in a case of iron deficiency anemia .
  • Decreased irritability is the first change of improvement noted after iron therapy is initiated.
  • The earliest indicator of response after starting iron in a 6-year-old girl with iron deficiency is Increase reticulocyte count.
  • Milk is not a good dietary source of iron.
  • Highest amount of iron is seen in red meat.
  • Iron absorption from intestine is regulated by mucosal block in the intestinal cells according to iron requirement.
  • Iron requirement in pregnancy is 35 mg.
  • Daily iron requirement in healthy Indian male is 17 mg.
  • Best test to detect iron deficiency in community is Serum Ferritin.
  • Tablets supplied by Govt. of India contains 100 mg elemental iron + 500 g Folic Acid.
  • Among the pulses,Soya bean has the highest content of iron .
  • Poor man's iron source is Jaggery.
  • Elemental iron supplementation in Iron deficiency anemia is 100 - 150 mg .
  • Most useful method of estimating total iron content of blood is ferritin.
  • Iron is transported bound to Transferrin.
  • Active absorption of iron decreases following gastrectomy.
  • Iron binding protein is Transferrin.
  • Haemaochromatosis is defined as Syndrome caused by systemic iron overload.
  • Iron deficiency anemia is seen in Chronic blood loss , Achlorhydria , Extensive surgical removal of the proximal small bowel.
  • Iron Deficiency anemia is commonly caused by Ankylostoma Duodenale.
  • Milk decreases the absorption of iron into the body.
  • Iron is absorbed in ferrous form.
  • Iron is stored in ferritin form.
  • Hypochromic Microcytic pattern in peripheral smear is seen in iron deficiency anemia.
  • Iron Dextran binds to transferrin and can be given IM or IV.
  • Hepcidin inhibits transfer of iron into enterocytes.
  • Ferritin biosynthesis is regulated by serum level of Iron.
  • Mentzer index more than 13 suggests a diagnosis of Iron deficiency anemia.
  • Bone marrow iron is decreased earlier than serum iron in Iron deficiency anemia.
  • Indications of Intravenous Iron administration : Iron malabsorption , Inability to Tolerate oral Iron , Patients on Erythropoietin Therapy.
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