Anemia

Anemia

Updated: 07/13/2024

© Jun Wang, MD, PhD

 

General features

  • Decrease in red cell mass
    • Hemoglobin: Levels of hemoglobin in a specific volume of whole blood
    • Hematocrit: Fraction of whole blood composed of red blood cells
    • Red cell count: Quantity of red cell in a specific volume of whole blood
  • Three major groups based on RBC sizes
    • Microcytic
    • Normocytic
    • Macrocytic
  • Three major causes
    • Blood loss: acute or chronic
    • Increased red cell destruction: hemolysis
    • Reduced production: marrow failure due to genetic abnormality or nutritional deficiency

Etiology

  • Genetic abnormality
    • Hemoglobinopathies
    • RBC cytoskeletal abomorlities
    • Enzyme abnormalities
    • Fanconi anemia
  • Nutritional deficiencies: iron, VB12, folate, general malnutrition
  • Physical etiologies: trauma, burns, frostbite, prosthetic valves, etc
  • Chronic diseases: chronic infections, neoplasia, autoimmune disorders, kidney or liver diseases, etc
  • Infectious diseases: hepatitis, sepsis, malaria, etc

Key pathogenesis

  • Tissue hypoxia due to impaired red cell function of oxygen delivery

Clinical presentations

  • Associated with tissue hypoxia due to reduced oxygen carrying capacity
  • Clinical presentations depends on speed of anemia onset, levels of Hb, underlying health conditions
  • Grading based on Hb levels (g/dL)
    • Mild (≥ 10)
    • Moderate (8-10)
    • Severe (6.5-7.9)
    • Life-threatening (<6.5)
  • Mild anemia might be asymptomatic
  • Severe anemia may cause high output heart failure
  • Symptoms
    • Weakness, fatigue, shortness of breath, etc.
    • Pica (desire to eat unusual and non-dietary substances)
  • Signs
    • Pale skin/mucosa
    • Orthostatic hypotension
    • Tachypnea and tachycardia
    • Signs associated with underlying diseases (hepatosplenomegaly, etc)

Diagnostic approaches

  • Investigation of etiology and underlying disorders
  • Peripheral blood test
    • Complete Blood Count
      • RBC count
      • Reticulocytes count: Quantity of reticulocytes in a specific volume of whole blod
      • Hemoglobin
      • MCV: Mean Corpuscular Volume, size of RBC, used to define microcytic, normocytic and macrocytic anemia
      • MCH: Mean Corpuscular Hemoglobin,  leves of hemoglobin in RBCs, used to define normochromic and hypochromic anemia 
      • RDW: Red Cell Distribution Width, variation in RBC sizes, elevated in iron deficiency anemia, thalassemia, sickle cell anemia, etc
    • Morphology of RBCs 
      • Anisocytosis: High variation of RBC sizes, elevated RDW
      • Poikilocytosis, abnormal shaped RBC, >10%
      • Spherocytes: Ball-shaped RBC, no central pallor area
      • Target cells: RBC with target or bull’s eye appearance
      • Fragmented RBC
    • Morphology of white cells and platelets
  • Other lab studies
    • Nutritional panels: Iron, folate, VB12 Proliferation panel: Erythropoietin
    • Hemolytic panels: Haptoglobin, bilirubin, LDH, etc
    • Liver function and renal function tests
    • Bone marrow evaluation

Morphological classification

Classification by pathogenesis

Decreased RBC Production
  • Acquired
    • Abnormal RBC metabolism
      • Nutritional deficiency
    • Acquired bone marrow failure
      • Autoimmune aplastic anemia
      • Myelophthistic (marrow replacement): neoplasia, myelofibrosis
Increased RBC Destruction/loss: Hemolytic anemia, acute and chronic hemorrhage

Management

  • Usually outpatient settings
  • Investigation of etiology
  • Treatment of underlying causes
    • Nutritional and dietary therapies
    • Bleeding control
    • Splenectomy
    • Bone marrow and stem cell transplantation
  • Transfusion: Usually NOT indicated if HB>7g/dl, or asymptomatic

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Contents

Pathology notes Jun Wang, MD, PhD 1. General information Frequently discussed syndromes Terms of dermatology Terms of hematology 2. Primary immunodeficiency disorders 3. Hemodynamic abnormalities Shock Thrombosis and embolism Bleeding disorders 4.  Benign blood cell disorders Anemia Benign white cell disorders 5. Hematopoietic neoplasms Lymphoid neoplasms Myeloid neoplasms Histiocytic neoplasms: Langerhans cell histiocytosis 6. Cardiovascular system Pulmonary hypertension Cardiovascular system tumors 7. Respiratory tract tumors 8. Gastrointestinal tract Congenital disorders Infectious gastroenteritis Oral cavity Esophagus Stomach Intestinal tumors Salivary glands Exocrine pancreas and gallbladder 9. Urinary system Kidney masses Lower urinary tract 10. Male reproductive system 11. Female genital tract 12. Breast 13. Endocrine organs Pituitary gland Adrenal gland Thyroid gland Parathyroid gland Endocrine pancreas M
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Practice questions Anemia I

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Practice questions Anemia I © Jun Wang, MD, PhD   Abbreviations: Hb: hemoglobin HCT: hematocrit MCV: Mean Corpuscular Volume MCHC: Mean Corpuscular Hemoglobin RDW: Red Cell Distribution Width TIBC: total iron binding capacity   1. Use this case for the next three questions . A 25-year-old woman is brought to the emergency department 2 hours after being involved in a motor vehicle accident. She is conscious but feels dizziness and weakness.   Her blood pressure is 90/60 mmHg, and her heart rate is 120 beats per minute. Physical examination reveals pale skin and mucosa and a 15 cm laceration on her left thigh with significant bleeding. What are most likely the CBC and TIBC results? A. Low Hb, low HCT, high MCV, high RDW, high TIBC B. Low Hb, low HCT, slightly low MCV, normal RDW, normal TIBC C. Low Hb, low HCT, slightly high MCV, normal RDW, normal TIBC D. Normal Hb, normal HCT, normal MCV, normal
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