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Approach to anemia

The same eight steps, every presentation: threats first, then the history and exam that discriminate, one honest sentence, a mechanism-grouped differential, and the tests read in order.

  1. Immediate threats

    • Active bleeding with hemodynamic change: the falling hemoglobin with a rising heart rate
    • Hemolysis with a rising bilirubin and a falling platelet count (thrombotic microangiopathy) needs the film today
    • Severe anemia with chest pain, dyspnea or syncope: the heart is short of oxygen
    • Pancytopenia with fever: marrow failure and neutropenic sepsis

  2. History that discriminates

    • Tempo: hours (bleeding, hemolysis) versus months (iron, B12, chronic disease)
    • Blood loss: melena, hematochezia, menorrhagia, hematuria; anticoagulants and antiplatelets
    • Diet, alcohol, malabsorption symptoms, gastric surgery, celiac features
    • Jaundice, dark urine, family history of hemolysis, drugs that hemolyse
    • Chronic disease, kidney disease, thyroid symptoms, weight loss, night sweats, bone pain

  3. Examination

    • Hemodynamics first: heart rate, postural drop, perfusion
    • Pallor, jaundice, koilonychia, glossitis, angular stomatitis
    • Lymphadenopathy, hepatosplenomegaly, bone tenderness, petechiae
    • Neurological signs of B12 deficiency: posterior column loss, peripheral neuropathy
    • A rectal examination when bleeding is possible

  4. Problem representation

    A slowly progressive microcytic anemia in a woman with menorrhagia and a low ferritin (iron deficiency) versus an acute normocytic drop with jaundice, a high reticulocyte count and a positive direct antiglobulin test (immune hemolysis).

  5. Differential, by mechanism

    Microcytic

    • Iron deficiency
    • Thalassemia trait
    • Anemia of chronic disease (some)
    • Sideroblastic anemia

    Normocytic

    • Acute blood loss
    • Anemia of chronic disease and kidney disease
    • Hemolysis
    • Marrow infiltration
    • Mixed deficiency

    Macrocytic

    • B12 and folate deficiency
    • Alcohol and liver disease
    • Hypothyroidism
    • Myelodysplasia
    • Drugs (methotrexate, hydroxyurea, zidovudine)
    • Reticulocytosis

  6. Investigations

    • Full count with the mean cell volume and red cell distribution width; a reticulocyte count on every anemia
    • The film, read by a person: fragments, spherocytes, target cells, blasts, hypersegmented neutrophils
    • Ferritin with a C-reactive protein, iron studies; B12 and folate; thyroid function; renal and liver panels
    • Hemolysis screen when suspected: bilirubin, lactate dehydrogenase, haptoglobin, direct antiglobulin test
    • Endoscopy for iron deficiency in a man or a post-menopausal woman; a marrow when two lines are down or blasts appear

  7. Interpretation

    • The reticulocyte count divides the world: high means loss or destruction, low means the marrow is not producing
    • Ferritin is an acute-phase reactant; a normal ferritin with a raised C-reactive protein does not exclude iron deficiency
    • A mean cell volume that is normal can hide a mixed deficiency; the red cell distribution width and the film find it
    • Fragments with thrombocytopenia are a microangiopathy until proven otherwise, and the answer is needed tonight

  8. Next steps

    • Transfuse for symptoms and thresholds, not for numbers; treat the cause in parallel
    • Iron deficiency has a source; the anemia is the symptom and the endoscopy is the diagnosis
    • Name the mechanism in the problem list, not just 'anemia'

Connected

AlgorithmWalk the anemia pathwayCompareIron deficiency vs thalassemia traitLabsThe hemolysis panel

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