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    Anemia- Diagnosis

    Hematological / Oncological

    Last Updated Sep 27, 2022
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    By Julian Marsden, Brenna Mackay

    Context

    • Anemia, or deficient or malfunctioning red blood cells (RBC), is the most common blood disorder that affects ~25% of people globally.
    • Three mechanisms: Blood loss, decreased RBC production, and increased RBC destruction.
    • Risk factors for anemia:
      • Most commonly seen in children, females, chronically ill, and elderly
      • Vegan diet -> Vit B12 deficiency anemia
      • Alcoholism -> folate deficiency anemia
      • Hereditary -> hemoglobinopathies
      • Intestinal disorders (ie. IBD)
      • Chronic diseases (ie. Kidney disease, Cancer, thyroid disease, liver disease, Rheumatoid arthritis or other autoimmune disease)
      • Infections
      • Menstruation
      • Pregnancy
    • Characterizing the anemia as microcytic, normocytic, or macrocytic using the MCV à helps to guide further investigations and management.

    Diagnostic Criteria

     Clinical Presentation

    • Weakness, general fatigue, dyspnea, tachycardia, dizziness, cold hands/feet, pallor.
    • Severity depends more on the rate of anemia development than the absolute Hemoglobin Hgb) value.
      • Acute -> life-threatening symptoms.
      • Chronic -> body compensates – greater loss of RBCs before symptoms appear.

     Diagnostic Criteria:

    • Adult non-pregnant females: Hgb < 120 g/L or Hct < 36% (0.36)
    • Adult pregnant females:
      • 1st trimester: Hgb < 110 g/L
      • 2nd trimester: Hgb < 105 g/L
      • 3rd trimester: Hgb < 110 g/L
    • Adult males: < 130 g/L or Hct < 41% (0.41)
    • Children and Adolescents:
      • Birth (term infant): < 135 g/L
      • 1 month: < 107g/L
      • 2 months: < 94 g/L
      • 3 – 6 months: < 95 g/L
      • 6 months – 2 yrs: < 105 g/L
      • 2 – 12 yrs: < 115 g/L
      • 12 – 18 years:
        • Males: < 130 g/L
        • Females: <120 g/L

    General laboratory Investigations

    • CBC:
      • Hemoglobin
      • Hematocrit
      • Complete WBC count
      • Differential WBC count
      • Platelet count
      • MCV
      • Mean corpuscular hemoglobin concentration (MCHC)
      • RDW (RBC distribution width)
    • Reticulocyte count
    • Peripheral blood smear

    Imaging

    • Imaging modality depends on suspected source.

    Characterize the Anemia

    • Microcytic = MCV <80 fL
      • Ddx:
        • Iron deficiency
          • Most common
          • Bleeding is the leading cause
        • Thalassemia
        • Anemia of chronic disease
      • Additional Labs:
        • Serum iron
        • Total iron binding capacity (TIBC)
        • Transferrin Saturation
        • Serum ferritin
          • Adults (ug/L):
            • < 15 = diagnostic of iron deficiency
            • 15-30 = probable
            • >30 = unlikely
            • >100 = normal
            • ≥600 = consider iron overload
          • Children (ug/L):
            • < 12 diagnostic of iron deficiency
            • 12-20 possible iron deficiency
    • Normocytic = Normal MCV: 80-100 fL
      • High reticulocyte count:
        • DDx:
          • Hemolytic Anemia – Inherited or Acquired
            • Sickle cell disease, thalassemia, microangiopathic hemolytic anemias
          • Blood loss
        • Additional Labs:
          • Serum Bilirubin
          • Lactate Dehydrogenase
          • Haptoglobin
        • Low reticulocyte count:
          • DDx:
            • With Pancytopenia:
              • Aplastic anemia
              • Leukemia
              • Bone marrow infiltration
              • Myelodysplastic Syndromes (MDS)
              • Myelofibrosis
              • TB
              • Amyloidosis
              • Drugs –ie. Chemotherapy
            • Non-Pancytopenia:
              • Red cell aplasia
              • Renal/Liver disease
              • Anemia of chronic disease
            • Additional Labs:
              • Renal function tests
              • Liver function tests
              • Erythropoietin
              • Bone marrow aspiration
    • Macrocytic = MCV >100 fL
      • Two types, megaloblastic (megaloblasts and hypersegmented neutrophils on peripheral smear) or non-megaloblastic.
      • DDX:
        • Non-megaloblastic:
          • Liver disease
          • Reticulocytosis
          • Alcoholism
          • Myelodysplasia
          • Hypothyroidism
        • Megaloblastic:
          • B12 deficiency
          • Folate deficiency
          • Drugs that impair DNA synthesis (Methotrexate, chemotherapy, sulfa)
        • Additional Labs:
          • Serum Vit. B12
          • Folate
          • TSH
          • Liver function panel

    Quality Of Evidence?

    Justification

    Evidence comes from reliable sources, which are in relative agreement on the diagnosis and investigations of anemia.

     

    Moderate

    Related Information

    OTHER RELEVANT INFORMATION

    Reference List

    1. Therapeutics Initiative. Intravenous (IV) iron for severe iron deficiency. TI UBC. 2015.


    2. Young MF, Oaks BM, Tandon S, Martorell R, Dewey KG, Wendt AS. Maternal hemoglobin concentrations across pregnancy and maternal and child health: a systematic review and meta-analysis. Ann N Y Acad Sci. 2019;1450(1):47-68.


    3. Wang M. Iron deficiency and other types of anemia in infants and children. AFP. 2016;93(4):270-8.


    4. Hayter J, Thomas A. Investigation and management of anaemia. Medicine. 2021 Feb 25.


    5. Long B, Koyfman A. Emergency Medicine Evaluation and Management of Anemia. Emerg. Med. Clin. 2018;36(3):609-30.


    6. Braunstein EM. Evaluation of Anemia. Merck Manual. 2020.


    7. Government of Canada. First Nations and Inuit Health Branch (FNIHB) Clinical Practice Guidelines for Nurses in Primary Care – Chapter 10 Hematology, Metabolism and Endocrinology. GC. 2010.


    8. Moses S. Anemia Chapter: Normocytic Anemia. Fpnotebook. 2020.


    9. British Columbia Ministry of Health. Iron Deficiency- Diagnosis and Management. BC Guidelines. 2019.


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