‘Iron Deficiency Anemia

Snapshot

• A 68-year-old man presents to his primary care physician with complaints of weakness and fatigue over the past half year. His medical history is significant for poorly-controlled diabetes. His family history is notable for type II diabetes in both of his parents and colon cancer in his father and older brother. A fecal occult blood test is performed and is shown to be positive for blood in the stool. A peripheral blood smear shows the following. 

Introduction

• Overview
  • iron deficiency anemia is a microcytic anemia that occurs when loss of iron exceeds intake
    • may occur with insufficienty dietary intake of iron or in the setting of chronic blood loss
    • treatment is usually with supplemental iron
• Epidemiology
  • incidence
    • most common anemia worldwide
    • over 12% of the world’s population are affected
  • demographics
    • most commonly seen in adolescent girls and women of childbearing age
      • due to blood loss from menstruation and childbirth
  • risk factors
    • pregnancy
    • menorrhagia
    • occult bleeding (i.e., gastrointestinal blood loss)
    • gastrointestinal parasites (i.e., hookworm), particularly in developing countries
    • celiac disease
• Pathophysiology
  • iron deficiency causes decrease in heme synthesis
    • decreased iron in the body may be due to
      • chronic or occult bleeding
        • colon cancer until proven otherwise in elderly 
      • dietary deficiency in children
        • high cow’s milk intake in infants  
          • cow’s milk is low in iron and causes poor absorption of iron
      • malabsorption
• gastrointestinal surgery

Presentation

• Symptoms
  • fatigue
  • weakness
  • pica (craving for non-nutritious substances, such as ice, metal, hair, and paint)
• Physical exam
  • conjunctival pallor
  • tachycardia
  • glossitis 
  • brittle nails
• restless leg syndrome

Studies

• Serum labs 
  • iron studies
    • ↓ serum iron
    • ↓ serum ferritin 
      • reflects low stores of iron in the body
      • confirms the diagnosis of iron deficiency
    • ↑ transferrin and total iron binding capacity (TIBC) 
  • complete blood count
    • ↓ RBC count
    • ↓ hemoglobin and hematocrit
    • ↓ absolute reticulocyte count
      • due to decreased production of RBCs
• Histology
  • peripheral blood smear
    • hypochromic and microcytic RBCs
• ↑ red cell distribution width (RDW)

Differential

• Thalassemia
  • key distinguishing factors
    • normal or ↑ RBC production
    • normal or ↑ RBC count on CBC
    • ↑ iron stores due to ineffective erythropoiesis and/or excessive blood transfusions
• Sideroblastic anemia
  • key distinguishing factors
    • presence of ringed sideroblasts on iron stain of a bone marrow aspirate
• ↑ iron stores

Treatment

• Lifestyle
  • supplementation with replacement iron
    • antacids may decrease iron absorption
  • avoid cow’s milk before 12 months of age and limit intake in patients 1-5 years old