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IRON DEFICIENCY & IDA Abdelaziz Elamin MD, PhD, FRCPCH Professor of Child Health College of Medicine Sultan Qaboos University Muscat, Oman [email protected] HIDDEN HUNGER The term was coined by WHO in 1986 & refers to the problems associated with the deficiency of 3 essential micronutrients: Iron Iodine Vitamin A LEARNING OBJECTIVES At the end of the lecture you will be able to: Discuss iron absorption, transport & stores Know the burden of IDA in the world Identify the causes & consequences of IDA Know how to diagnose IDA Recognize the strategies for control & prevention of IDA IRON IN NATURE Iron is among the abundant minerals on earth. Of the 87 elements in the earth’s crust, Iron constitutes 5.6% and ranks fourth behind Oxygen (46.4%), Silicon (28.4%) and Aluminum (8.3%). In soil, Iron is 100 times more than Ca, Na & Mg and1000 times more than Zinc and 100,000 times more than Iodine. IRON DEFICIENCY Iron deficiency is the most common micronutrient deficiency in the world affecting 1.3 billion people i.e. 24% of the world population. In comparison only 275 million are iodine deficient and 45 million children below age 5 years are Vitamin A deficient. IRON DEFICIENCY /2 Iron deficiency can range from sub-clinical state to severe iron deficiency anemia. Different stages are identified by clinical findings & lab tests. Anemia is defined as a hemoglobin below the 5th percentile of healthy population. Most studies showed this cutoff point to be around 11 g/dl (-2SD below the mean). HB IN IDA AT RISK GROUPS Infants Under 5 children Children of school age Women of child bearing age PREVALENCE OF ID Region South Asia Africa Latin Am Gulf Arabs Developed World 0-4yr 56% 56% 26% 40% 12% 43% 5-12yr 50% 49% 26% 36% 7% 37% Women 58% 44% 17% 38% 11% 35% ETIOLOGY Inadequate intake of iron & of food, which enhances iron absorption. High intake of inhibitors of iron absorption Hookworm infestation. Blood loss (heavy menses & use of aspirin & NSAID). High fertility rate in womem. Low iron stores in newborns. DIETARY IRON There are 2 types of iron in the diet; haem iron and non-haem iron Haem iron is present in Hb containing animal food like meat, liver & spleen Non-haem iron is obtained from cereals, vegetables & beans Milk is a poor source of iron, hence breastfed babies need iron supplements IRON ABSORPTION Haem iron is not affected by ingestion of other food items. It has constant absorption rate of 20-30% which is little affected by the iron balance of the subject. The haem molecule is absorbed intact and the iron is released in the mucosal cells. IRON ABSORPTION (2) The absorption of non-haem iron varies greatly from 2% to 100% because it is strongly influenced by: The iron status of the body The solubility of iron salts Integrity of gut mucosa Presence of absorption inhibitors or facilitators INHIBITORS OF IRON ABSORPTION Food with polyphenol compounds Cereals like sorghum & oats Vegetables such as spinach and spices Beverages like tea, coffee, cocoa and wine. A single cup of tea taken with meal reduces iron absorption by up to 11%. OTHER INHIBITORS Food containing phytic acid i.e. Bran, cereals like wheat, rice, maize & barely. Legumes like soya beans, black beans & peas. Cow’s milk due to its high calcium & casein contents. INHIBITION-HOW? The dietary phenols & phytic acids compounds bind with iron decreasing free iron in the gut & forming complexes that are not absorbed. Cereal milling to remove bran reduces its phytic acid content by 50%. Promoters of Iron Absorption Foods containing ascorbic acid like citrus fruits, broccoli & other dark green vegetables because ascorbic acid reduces iron from ferric to ferrous forms, which increases its absorption. Foods containing muscle protein enhance iron absorption due to the effect of cysteine containing peptides released from partially digested meat, which reduces ferric to ferrous salts and form soluble iron complexes. IRON ABSORPTION (3) Some fruits inhibit the absorption of iron although they are rich in ascorbic acid because of their high phenol content e.g strawberry banana and melon. Food fermentation aids iron absorption by reducing the phytate content of diet IRON TRANSPORT Transferrin is the major protein responsible for transporting iron in the body. Transferrin receptors, located in almost all cells of the body, can bind two molecules of transferrin. Both transferrin concentration & transferrin receptors are important in assessing iron status. STORAGE OF IRON Tissues with higher requirement for iron ( bone marrow, liver & placenta) contain more transferrin receptors. Once in tissues, iron is stored as ferritin & hemosiderin compounds, which are present in the liver, RE cells & bone marrow. The amount of iron in the storage compartment depends on iron balance (positive or negative). Ferritin level reflects amount of stored iron in the body & is important in assessing ID. IRON CYCLE IN THE BODY ROLE OF IRON IN THE BODY Iron have several vital functions Carrier of oxygen from lung to tissues Transport of electrons within cells Co-factor of essential enzymatic reactions: Neurotransmission Synthesis of steroid hormones Synthesis of bile salts Detoxification processes in the liver DIAGNOSIS OF IDA Clinical: symptoms (fatigue, dizziness , palpitations..etc) & signs (pallor, smooth tongue, Koilonychia, splenomegaly & dysphagia in elderly women). Laboratory Stainable iron in bone marrow Response to iron supplements LAB FINDINGS IN IDA Microcytic hypochromic anaemia Low Hb level (< 11.0 g/dl) Low MCV, MCH, MCHC Low serum ferritin High RWD High iron binding capacity High erythrocyte protoporphyrin Normal Blood Film MICROCYTES HYPOCHROMIA Consequences of Iron Deficiency Increase maternal & fetal mortality. Increase risk of premature delivery and LBW. Learning disabilities & delayed psychomotor development. Reduced work capacity. Impaired immunity (high risk of infection). Inability to maintain body temperature. Associated risk of lead poisoning because of pica. MANAGEMENT OF IDA Blood transfusion if heart failure is eminent IV or IM iron in pregnant women Oral iron 3-5 mg Fe/kg/day Treat underlying cause Dietary education PREVENTION OF IDA Dietary modification Food fortification Iron supplementation PREVENTION OF IDA /2 Diet & nutrition education eat more fruits and vegetable no coffee or tea with meals programmes should be targeted to at risk groups reduce phytic content of cereals and legumes by fermentation PREVENTION OF IDA /3 Short term approach: supplementation with iron tablets. Long-term approach: food fortification with iron either for the whole population (blanket fortification) or for specific target groups like infants. It requires no cooperation from users unlike taking iron supplements. FOOD FORTIFICATION Iron compounds used in food fortification can be divided into 4 groups Freely water soluble (ferrous sulphate, gluconate, lactate & ferric ammonium citrate). Poorly water soluble (ferrous fumarate, succinate & saccharate). Water insoluble (ferric pyrophosphate, ferric orthophosphate & elemental iron). Experimental (sodium-iron EDTA & bovine Hb concentrate). Which iron form to use? The major factors governing the choice of iron compound include: Bioavailability Organoleptic problems Cost Safety Ideally we should go for a safe, cheap, highly bioavailable iron, which causes no organoleptic side-effects Which iron form to use? • Freely water soluble iron are the most bioavailable, but causes unacceptable colour & flavour change in many foods. • Insoluble iron compounds are inert with no organoleptic effects but it is poorly absorbed • Cost-wise elemental iron is the cheapest, ferrous sulphate costs 10 times more, but most expensive is EDTA • Safety is of concern with EDTA & Bovine Hb only because of potential problems COMMON PRACTICE Ferrous sulphate is commonly used in Rx & prevention of IDA because of good absorption & high bioavailability, but it has its drawbacks GIT disturbances & staining of teeth are frequent Effects on fortified foods may include: Fat oxidation & rancidity Colour changes Metallic taste Precipitation EXPERIMENTAL COMPOUNDS EDTA (Ethylene Diamine Tetra-Acetate) molecule has 4 negative charges to which any metal can be attached to form stable complex. The metal incorporated into EDTA can be replaced by a metal of higher affinity or released at a certain PH. Food is usually fortified by both Fe-EDTA & Na or Ca EDTA. HOW EDTA ACTS? Fe EDTA is stable in the acidic PH of the stomach, but dissociate in the alkaline PH of the duodenum releasing ferrous ions ready to be absorbed. while the Na-Ca EDTA dissociate in the stomach releasing Na & Ca and taking iron from the food instead to form Fe EDTA which dissociate in the duodenum. ADVANTAGES OF USING EDTA Iron absorption is 6 times greater than with ordinary methods even in the presence of inhibitors. No need to add vitamin C or other promoters to enhance iron absorption. No change in colour or flavour of food with EDTA even when stored for long time. LIMITATIONS of EDTA USE EDTA fortification is 7 times more expensive than ordinary fortification using iron salts. Health care providers have little experience with this new technique.