Lab

CD4 Cell Count

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CD4 Cell Count, CD4 Count

  • See Also
  1. Absolute Lymphocyte Count Estimation of CD4 Count
  • Indication
  1. Detecting HIV related Immune Deficiency (most accurate measure)
  2. Monitoring HIV Disease
  3. Used in combination with Plasma Viral Load Testing
  • Efficacy
  1. Advantages
    1. Best marker of of Immune SystemImpairment
    2. Roughly correlated to duration and activity of HIV Infection
    3. Best predicts prognosis
  2. CD4 Cell Counts have variability
    1. Vary from person to person even given the same HIV severity
    2. Vary widely from lab to lab
      1. Use the same lab to follow patients
    3. Diurnal CD4 Cell Count variation (from 50-150 cells/mcl)
    4. CD4 Count may drop 50% with acute comorbid illness (e.g. Influenza, Pyelonephritis)
  • Labs
  • Normal
  1. Non-HIV patients: 800-1200 cells/mcl
  • Labs
  • Interpretation
  1. See HIV Course
  2. Each CD4 Count 10% rise decreases progression risk 15%
  3. Stage 1: CD4 500 Cells/mm3 or more
  4. Stage 2: CD4 200 to 499 Cells/mm3
  5. Stage 3: CD4 <200 Cells/mm3 or AIDS-Defining Illness
  • Labs
  • Surrogates for CD4 Count
  1. Patient medical records and CD4 Count may be unavailable to emergency providers
  2. Surrogates for low CD4 Counts <200 Cells/mm3
    1. Absolute Lymphocyte Count (ALC) <1000 to 1250 cells/mm3
      1. See Absolute Lymphocyte Count Estimation of CD4 Count
    2. Prophylactic Antibiotic daily use found on medication reconciliation
      1. Trimethoprim-Sulfamethoxazole
      2. Dapsone
      3. Pentamidine
      4. Azithromycin
      5. Fluconazole
  • References
  1. Parker and Bond (2023) Crit Dec Emerg Med 37(10): 4-9
  2. GoldSchmidt (2016) Am Fam Physician 94(9): 708-16 [PubMed]
  3. Hughes (1997) Ann Intern Med 126:929-38 [PubMed]
  4. Mellors (1997) Ann Intern Med 126:946-54 [PubMed]
  5. O'Brien (1997) Ann Intern Med 126:939-45 [PubMed]