Iron Deficiency Anemia

Iron is an important mineral element needed by all forms of life. It is most commonly found existing as Iron ॥ (Fe²⁺)   or Iron॥। (Fe³⁺). Free iron can cause tissue damage; thus, in the body, Iron is bound to proteins and its concentration is tightly regulated especially because the body has no way of excreting excess iron.  Such metalloproteins containing iron include heme proteins, transport /storage proteins and metalloenzymes. Heme is a group containing a porphyrin ring with an atom of iron at its core.

                                              

It is important in the transport of oxygen, which is carried bound to its Iron core. For this function, 4 molecules of the iron-bearing heme are coupled to 4 globin protein molecules (usually 2α and 2β globin chains) to form hemoglobin. Hemoglobin picks up oxygen from the pulmonary blood which has high oxygen content, low CO₂ and high Ph, and drops it in the tissues which have low oxygen, high CO₂ and low Ph. i.e. the Bohr Effect. One molecule of human hemoglobin can carry up to 4 molecules of oxygen.

Hemoglobin is mainly found in red blood cells. In fact, it is responsible for the red colour of blood. It is synthesized in maturing red cells; the heme part in the mitochondria and then cytosol, and the protein (globin) part in the ribosomes. Decrease in the synthesis of hemoglobin results in anemia. Anemia is defined as a decrease in the number of red blood cells or the amount of hemoglobin in the blood. The most common cause of anemia is iron deficiency. A low level of iron in the body negatively impairs the synthesis of hemoglobin and thus reduces the capacity of the blood to carry oxygen to tissues even in the presence of adequate oxygen tension.

Iron is obtained from food, absorbed in the gastrointestinal tract (mostly in duodenum) into enterocytes, taken across the enterocytes cell membrane by ferroportin, and transported in blood by transferrin to the bone marrow for red cell production, and to other tissues where it’s used. A small excess is stored as ferritin and hemosiderrhin. About 1mg of iron is lost daily in desquamated cells of skin and intestinal lining. This amount also corresponds to the amount absorbed from food daily even though the average diet contains up to 10-15mg of iron/day. The amount absorbed may however increase if there is an increase in the amount lost e.g. during bleeding. Sources of dietary iron include red meat, beans, lentils, black eyed peas, poultry, fish, green leafy vegetables, molasses and fortified foods like cereals. The animal sources contain heme iron (from blood and other hemoproteins) and non heme iron while the vegetable sources contain mostly non heme iron. Heme iron is easier to absorb than non heme iron which also requires ascorbic acid (Vit C) for absorption. Also, some substances such as phytates, oxalates, phosphates, carbonates, and tannates present in many plants such as grains, nuts, beans, spinach and lentils, chelate  non heme iron and reduce its absorption. The presence of meat and vitamin c in a meal therefore improves the absorption of iron.

Iron deficiency can result from changes at different points on the iron metabolism journey.

  ·         Inadequate intake: Diet low in iron rich food

  ·         Reduced absorption: usually due to disease or resection of the small bowel where iron is absorbed

Causes of Iron deficiency

·         Increased body requirements: This occurs during active growth for instance in children and adolescents who are thus more susceptible to iron deficiency, during pregnancy and lactation.

 ·         Excessive loss: Body loss can increase tremendously during active bleeding from just about 1mg/day to a level that cannot be compensated by increased intestinal absorption. Women are more prone to iron deficiency due to menstrual loss especially if there’s menorrhagia. Peptic ulcer disease is a common cause of GI bleeding. Also, Hook worm infestation is a cause of chronic intestinal blood loss and is an important cause of anemia in areas where infestation is common.

Lifecycle of hook worm

Symptoms of iron deficiency anemia include the following:

·         Pale skin and mucous membranes

·         Tiredness/fatigue/weakness

·         Breathlessness

·         Sleepiness

·         Palpitations

·         Irritability

·         Anorexia

·         Fainting

These are all symptoms common to any form of anemia. Symptoms peculiar to iron deficiency may include:

·         Pica

·         Glossitis  (Plummer–Vinson syndrome also called Paterson–Brown–Kelly syndrome)

·         Dysphagia (Plummer–Vinson syndrome also called Paterson–Brown–Kelly syndrome)

·         Hair loss

·         Grooved nails

Consequences of iron deficiency in children include:

·         Learning difficulties

·         Slow social development

·         Slow physical growth

·         Low IQ

Diagnosis can often be made from the symptoms and signs. However, lab investigations may be needed especially in mild cases with less obvious symptoms.

·         Complete blood count shows low Hb, low Hematocrit, high red cell distribution width

·         Peripheral blood smear shows hypochromia with initially normocytic cells (normal sized cells) followed by a mixed picture followed by microcytosis at about the 120^th day when all normal sized cells existing before the iron deficiency have been destroyed.

·         Low MCV, low MCH, low MCHC

·         Low serum ferritin, low serum iron, high transferrin(increased absorption), high total iron binding capacity (TIBC)

·         Low iron saturation (serum iron to TIBC ratio)

Treatment involves identifying the cause and correcting if possible, and taking iron supplements such as ferrous gluconate.

 Ascorbic acid supplements can also improve iron absorption. Screening for and treating iron deficiency anemia is very important in pregnant women, infants and children, in areas where iron deficiency is common. This is because of the severe irreversible consequencies on the developing brain.