Anemia – Part 2 – Iron Deficiency Anemia, Microcytic and hypochromic anemia
- Take the blood in the EDTA.
- Make fresh peripheral blood smear.
- For iron, draw the first-morning blood sample because of the diurnal variation.
- Iron deficiency anemia is the most common cause of anemia, and iron is the most common dietary deficiency globally.
- Iron deficiency results in decreased quantity defect in hemoglobin production, which leads to small, pale microcytic, and hypochromic RBCs.
- DNA synthesis is normal.
- Iron-deficiency anemias are divided into three groups:
- Iron metabolism where there is iron deficiency.
- Disorders of heme synthesis seen in sideroblastic anemia.
- Disorder of globin protein synthesis seen in Thalassemia.
The anemia is caused by:
- Inadequate intake of iron:
- Meat, eggs, and green leafy vegetables are a good source of iron.
- Pregnant ladies and children need a more iron-rich diet.
- Pregnancy or increased blood loss in menstruation leads to iron deficiency.
- Internal bleeding in stomach ulcers and polyps of GIT.
- Too much use of aspirin may cause internal bleeding.
- Esophageal varices.
- In the case of partial gastrectomy.
- Carcinoma of the stomach, caecum, colon, or rectum.
- Bleeding from the hemorrhoids.
- Rarely hematuria, hemoglobinuria, and self-inflicted blood loss.
- Parasitic infestation by the hookworm.
- Malabsorption like Gluten-induced enteropathy and gastrectomy.
- Inability to absorb iron from GIT like in bypass surgery of stomach or intestine and Celiac disease.
- In the case of gastric, duodenal, or jejunal resection.
- People at risk of developing iron deficiency are:
- Ladies of childbearing age period.
- People with a poor diet.
- People who frequently donate blood or professional donors.
- Vegetarian who does not eat meat or iron-rich foods.
- Infants or children who are mainly in milk and do not take solid foods.
- Poor diet in poor people.
- Pregnancy and lactation, where more iron is needed. In pregnancy, iron needs maybe around 1000 mg. There is an increased maternal red cell mass of roughly 35%. There is the diversion of the iron to the fetus.
- There is 300 mg of iron transfer to the fetus.
- There is blood loss during the delivery.
- Iron supplement needed if the Hb is below 10 g/dL or MCV is <82 fL in the third trimester.
Causes of iron deficiency anemia:
- Stages of iron deficiency:
- Decreased Iron stores: Iron stores are depleted. There is decreased serum ferritin.
- Defective hemoglobin synthesis: There is a deficiency of iron, which will lead to defective hemoglobin synthesis.
- There will be decreased serum iron.
- There is decreased transferrin saturation.
- There is an increased RBC protoporphyrin.
- There is an increased total iron-binding capacity (TIBC);
- The patient will be anemic.
- Development of anemia: There will be hypochromic and microcytic anemia. The patient will show:
- Low Hb.
- Decreased Hct.
- Decreased RBC count.
- Decreased MCV.
- It is increased serum soluble-transferrin receptors.
- Iron is one of the most important components of hemoglobin.
- Decreased iron in hemoglobin leads to anemia.
- Hemoglobin contains roughly 37% of the iron by weight.
- The iron is taken as ferric form, and it changes to the ferrous form in the stomach by the Hydrochloric acid.
- It is then absorbed mainly in the small intestine.
- The leftover is excreted in the feces.
- The body uses 1 mg per day of iron, and there is the storage of iron 1000 mg.
- It then combines with the apoferritin with the protein and makes a complex of ferritin.
- Iron is stored as ferritin in the body.
- Now Ferric ions combine with the Transferrin, which is synthesized in the liver.
- Transferrin helps:
- Make an iron insoluble form.
- It prevents iron-mediated free radical toxicity.
- This facilitates iron transport into the cells.
- Iron is stored as ferritin in hepatocytes, macrophagic cells (bone marrow), RBCs, and the muscles.
- Ferritin release iron for the formation of hemoglobin and heme protein.
Signs and symptoms of Iron deficiency anemia are:
- Iron deficiency anemia is more common in children, young females, and older people.
- There is an increased need for infants, children, and pregnant women.
- In females, iron deficiency occurs due to menstrual cycles.
- Chronic loss of blood from the GI tract is the usual reason for iron deficiency.
- There are general fatigue and weakness.
- Skin is pale, and also conjunctiva will be pale.
- The patient may feel dizziness.
- These patients, particularly children, have a craving to eat dirt, ice, or clay. Sometimes these children lick the walls.
- There may be a feeling of tingling or crawling in the legs.
- Patients have cold hands and feet.
- These patients may have tachycardia, as fast or irregular heartbeat.
- Sometimes have a headache.
- Nails are brittle.
- The tongue has soreness or swelling.
- There is a case report of renal cell carcinoma with microcytosis and normochromic anemia.
Complications of Iron deficiency anemia are:
- There is tachycardia and may lead to heart failure and an enlarged heart.
- In pregnancy, there may be premature birth and low weight of the baby.
- Children and infants may have delayed and developmental abnormalities.
Iron deficiency anemia lab findings:
- Decreased serum ferritin is the early sign and followed by a decrease in the % saturation of transferrin, decreased serum iron, and increased zinc protoporphyrin (ZPP).
- Later on, hemoglobin will fall.
- MCV is reduced to 50 to 60 fl (where the normal value is 77 to 93 fl).
- MCH is reduced to 15 to 20 pg (where the normal value is 27 to 32 pg).
- MCHC is reduced to 20 to 25 g/dl (where the normal value is 31 to 35 g/dl).
- The serum iron level is decreased (very low). Normal serum iron is 50 to 150 µg/dL.
- The serum ferritin level is low <10 ng/dL.
- Raised total iron-binding capacity (TIBC). Normal TIBC is 250 to 450 µg/dL.
- Percent transferrin saturation normal value is 20% to 50%, and normally transferrin 33% saturated.
- RBC protoporphyrins increased.
- The peripheral blood smear shows anisocytosis, poikilocytosis with the presence of target cells.
- There are microcytic, hypochromic red blood cells.
- There may be leucopenia.
- The serum transferrin receptor is raised.
- Platelets count high.
- RDW is high.
- Bone Marrow shows erythroid hyperplasia, and this is polychromatic.
- Micro-normoblasts are seen.
- The cytoplasm is decreased and sometimes shows the only rim.
- Nuclei may be pyknotic.
- Erythroblast iron is absent.
- Myeloid series is usually normal, and M: E ratio is reduced.
- Megakaryocytes are normal in number and morphology.
- Micro-normoblasts are seen.
- The iron stain of bone marrow shows the absence of stainable iron in the reticulum cells, and normoblast looks like sideroblasts. This is a more reliable test by Prussian blue reaction.
Lab findings in iron deficiency anemia:
Test Result Hemoglobin Normal or low MCH Decreased MCV Decreased <80 fl MCHC Decreased RDW Increased Reticulocytes Decreased Total iron Decreased (normal =50 to 150 µg/dL) TIBC Increased (normal = 250 to 450 µg/dL) Ferritin Decreased (normal = 20 to 250 ng/mL) Transferrin receptor Increased % transferrin saturation Decreased (normal 20% to 50%) Platelet count High WBC Leucopenia Bone marrow iron store Decreased or absent Erythroblast iron Absent Free RBC protoporphyrin Increased
Summary of the lab findings of Iron-deficiency anemia:
|lab test||Lab findings|
Differential diagnosis of Microcytic hypochromic anemia:
|Anemia type||Serum iron||TIBC||Ferritin||RDW||HbF||HbA2||FEP|
|Iron-deficiency||Low||High||Low||High||Normal to low||Normal||High|
FEP = Free erythrocytes protoporphyrin.
TIBC = Total iron-binding capacity.
RDW = Red cell distribution width.