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Iron Deficiency Anemia
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Iron Deficiency Anemia

Topics / Medical / Blood and Related Disorders

Basics

Anemia is described by the EML as an, “reduction in the absolute number of circulating red blood cells and most commonly diagnosed when the hemoglobin concentration is reduced below the reference range for age and gender”

This type of anemia is due to a decreased in iron. It is a commonly caused by either: increased iron demand, increased iron loss or decreased iron intake/absorption. In South Africa, it is commonly caused by either chronic blood loss, poor iron absorption or due to a nutritional cause.

It is important to understand that iron is absorbed primarily in the duodenum. The it binds to a carried protein called transferrin which is responsible for transporting iron in the blood. Iron is then stored in two forms: short-term storage (ferritin) and long-term storage (hemosiderin).

Causes

  1. Increased iron demand
    1. Rapid growth during infancy or adolescence
    2. During pregnancy
    3. During usage of erythropoietin therapy
  2. Increased iron loss
    1. Chronic blood loss
    2. Menses, especially if heavy
    3. Patient donates blood
    4. Frequent phlebotomy as a treatment of polycythemia vera
  3. Decreased iron intake/absorption
    1. Inadequate diet
    2. Malabsorption of iron due to disease (IBD) or surgery (post gastrectomy)

Presentation

  1. General symptoms/signs of anemia: e.g fatigue, pallor
  2. Specific symptoms/signs of iron deficiency: Glossitis, koilonychias, post-cricoid web

Investigations

  1. There is an article that describes a bit more general investigations for anemia.
  2. Findings
    1. Low MCV (microcytic) and MCH (hypochromia)
    2. FBC Smear: Hypochromic, microcytic anemia
    3. Iron studies: Low Ferritin, low serum iron, high/normal total iron binding capacity, high transferrin, low transferrin saturation, decreased bone marrow storage of iron (low hemosiderin)
    4. You also need other investigations to find out the cause of the anemia. In patients that are at high risk may benefit from upper/lower endoscopic investigations to find out the cause of the anemia.
Iron Deficiency Anemia Anemia of Chronic Disease
Iron Reduced Reduced
Transferrin Increased Reduced to normal
Transferrin Saturation Reduced Reduced
TIBC High Normal/low
Ferritin Reduced Normal to increased
RDW High Normal
MCV Low Normal (low in 30% of the patients)
Bone Marrow Iron Absent Present
Erythropoietin Level Very high Inappropriately low for the degree of anemia

Treatment

  1. Treat the underlying cause
  2. Oral Iron Supplementation
    1. Ferrous sulphate PO 170mg (±55mg elemental iron) 12 hourly OR Ferrous fumarate PO 200mg (±65mg elemental iron) 12 hourly
    2. Follow up the patient after 1 month of treatment
    3. Should expect at least 2g/dl increase in Hb
  3. Parenteral Iron Supplementation
    1. May be associated with anaphylaxis
    2. It is ONLY indicated in the following conditions
      • Oral iron supplementation is ineffective after three months of treatment
      • There is iron deficiency anemia after 36 weeks of pregnanc
      • There are indicators that may suggest that oral therapy will be ineffective (malabsorption)
      • Oral iron therapy is not tolerated by the patient
    3. Warning: Ideally, one should discuss this with their consultant. Keep in mind that these patients may develop anaphylaxis so you need a resuscitation trolley near by. For every gram of Hb that is below the normal, you will need 250mg of iron.
    4. Dose: Iron sucrose 200mg in 200ml of Normal Saline (NS) over 30mins on alternate days until the desired level is reach OR Iron Dextran total daily dose of 20mg/kg (requires a test dose of 25mg in 100ml NS infused over 15mins then monitor the patient for 1 hour. If no side effects, complete the rest of the dose in a 500ml NS over 4-6 hours and then observe the patient for a further 1 hour.
  1. Transfusions
    • Indications
      1. Patient has an anemia that has caused symptoms of heart failure or with symptoms of respiratory distress
      2. There is active or ongoing bleeding
      3. Correction of the anemia is necessary for an urgent invasive procedure or surgery.

Prophylaxis

May be give to patients who are prone to developing iron deficiency, such as pregnancy.

    1. Ferrous sulfate PO 170mg (±55mg elemental iron) daily OR Ferrous fumarate PO 200mg (±65mg elemental iron) daily
    2. If the patient cannot tolerate this due to side effects (epigastric pain, nausea, vomiting and constipation), you should prescribe intermittent iron supplement.
      1. Ferrous sulphate PO 340mg PO once per week (±110mg elemental iron) WITH meals OR Ferrous fumarate PO 400mg once per week (±120mg elemental iron)
Published on 16 August 2022
Dr. RW Becerra Estevez
Dr. RW Becerra EstevezMBChB (WSU)

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