Physician Assistant Exam Review

You are here: Home / Hematology / S2 E075 Microcytic Anemia and a Better Way to Remember

S2 E075 Microcytic Anemia and a Better Way to Remember

Podcast: Play in new window | Download

Anemia

Anemia means low RBC or Hgb count. A patient could be bleeding out and have a low Hgb or they could have a dietary deficiency. Anemia is a starting place. As we get more detailed and more specific we can get a more clear diagnosis and treatment plan. One of the easiest places to start getting a more clear picture of anemia is with the size of the the red blood cells.

Definitions

  • Target Cells
    • Red blood cells which appear pale centrally and red around the rim (like a bullseye)
    • These can be seen in
      • Obstructive liver disease
      • Thalassemia
      • Hemoglobin C and D disease
      • Sickle-cell disease
      • Iron deficiency anemia
      • Post splenectomy
  • Hypochromic - Cells appear pale under microscope due to lack of Hgb
  • Red Blood Cell Distribution Width (RDW)
    • Measurement of red cells size variability
  • Anisocytosis red blood cells vary in size
  • Poikilocytosis – red blood cells have abnormal shapes

Microcytic Anemia

  • MCV < 80
  • All microcytic anemias have a low retic count.
    • Poor RBC production = low retic count
  • Types of microcytic anemia
    • Iron deficiency
    • Thalassemias
    • Sideroblastic anemia (Think lead poisoning)
    • Anemia of Chronic Disease

Iron Deficiency

Iron deficiency is the most common cause of microcytic anemia

Causes of iron deficiency

  • Occult blood loss
    • GI bleed (think NSAID use)
    • Irregular uterine bleeding
  • Decreased iron intake (children/pregnant women/malnutrition)
  • Decreased iron absorption
    • Gastric surgery

Clinical Presentation

  • Fatigue
  • Irritability
  • Mouth ulcers
  • Palpitations
  • Brittle nails
  • Pallor
  • Smooth tongue
  • Angular cheilitis – Inflammation at the corners of the mouth
  • Dysphagia
  • Pica – eating non food items including dirt, paper, hair and ice
  • Incidental lab finding during routine clinical evaluation

Labs and Studies

  • CBC
    • Hgb and HCT are decreased
    • Microcytic
    • Decreased retic count
    • Increased Red Blood Cell Distribution Width (RDW)
      • RBC’s are of varying sizes
      • Anisocytosis
  • Peripheral blood smear
    • Hypochromic
    • Target Cells
  • Iron studies
    • Ferritin
      • Protein used to store iron
      • Plasma ferritin < 10 in women and < 30 in men (diagnostic)
    • Transferrin = transport protein for iron or iron binding capacity
    • Total Iron binding capacity (TIBC)
      • Elevated
      • Total transferrin is elevated while transferrin saturation is low < 15%
    • Serum iron is low < 30

Treatment

  • Ferrous sulfate 325 TID x 6 months is the standard treatment
    • May cause constipation
  • Patients with iron deficient anemia should be worked up for occult bleeding

Thalassemias

  • Important genetic information
    • Alpha Thalassemia – Southeast Asia, China, Middle East or African descent
    • Beta Thalassemia – Mediterranean descent

For both Alpha and Beta Thalassemia there are two types

  • Minor = gene only inherited from one parent
    • Alpha and Beta thalassemia minor have few or no symptoms
  • Major = gene inherited from both parents
  • Alpha Thalassemia major = Bart’s Hgb
    • Hydrops fetalis
      • Fluid management problem in a fetus secondary to anemia and the extra work the heart is doing to move blood around body. The mortality rate is as high as 50%
  • Beta Thalassemia major = Cooley’s anemia
    • Born without a problem, but develop severe anemia over the first year as the fetal Hgb is no longer available
    • Typically patients do not survive past 30 years old

Symptoms

  • Bone issues – pathologic fractures, abnormal facial structures
  • Splenomegaly
  • Jaundice
  • Severe anemia
  • Osteopenia
  • Fatigue, shortness of breath

Labs

  • Definitive diagnosis = electrophoresis
  • Serum ferritin is elevated
  • Hgb very low around 3-6
  • Normal or elevated retic count
  • Microcytic
  • Peripheral blood smear
    • Target cells
    • Basophilic stippling (associated with Beta thalassemia, lead poisoning and sideroblastic anemia)
    • Heinz bodies with Alpha thalassemia

Treatment

  • Folic acid
  • Serial blood transfusions but watch for iron overload
  • Genetic counseling
  • Splenectomy

Sideroblastic Anemia

  • Most frequently acquired conditions but may be congenital.
  • Characterized by decrease in Hgb and and increase in iron.
  • Ways of acquiring a sideroblastic anemia
    • Lead poisoning
    • Alcoholism
    • Myelodysplasia

Labs

  • Lead levels
  • CBC
  • Peripheral blood smear
    • Basophilic stippling if due to lead poisoning
  • Diagnostic test – Prussian blue staining of bone marrow will show ringed sideroblasts

Treatment

  • Treat underlying cause
    • Chelation therapy for lead poisoning
  • Transfuse as necessary

Anemia of Chronic Disease

  • Any ongoing disease state that causes inflammation may lead to issues with absorbing and releasing iron, poor production of RBCs and shorter RBC lifespan.
  • Examples of possible chronic diseases
    • Rheumatoid arthritis
    • Cancer
    • Lasting infection
    • Kidney disease

Labs and Studies

  • Initially normocytic then progressing to microcytic
  • Hgb generally less than 8

Treatment

  • Treat underlying disease
  • Blood transfusion

Differentiating Microcytic anemias

  • Hypochromic = Iron deficiency
  • Target cells – If microcytic then Thalassemia
  • Heinz bodies – if microcytic anemia then Thalassemia
  • TIBC increased = Iron deficiency
  • TIBC decreased = Chronic disease
  • Terms that are only marginally helpful
    • Heinz bodies
      • Found in
        • Thalassemia
        • Hemolytic anemia
        • G6PD deficiency
    • Basophilic stippling
      • Found in
        • lead poisoning
        • Thalassemia
        • Sickle cell
        • Anemia from B12 / folate deficiency