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Hematocrit

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Hematocrit, Hct, Hematocrit Cutoffs for Anemia

  • Calculation
  1. Hct = Mean Corpuscular Volume x Red Blood Cell Count
  • Normal Values per age (-2 SD to +2 SD)
  1. Birth: 42 to 64% (mean 51%)
  2. Age <1 month: 31 to 67% (mean 44%)
  3. Age 1-2 months: 28 to 55% (mean 35%)
  4. Age 2-6 months: 28 to 42% (mean 36%)
  5. Age 0.5 - 2 years: 33 to 40% (mean 36%)
  6. Age 2 to 6 years: 34 to 40% (mean 37%)
  7. Age 6-12 years: 35 to 45% (mean 40%)
  8. Female
    1. Age 12-18 years: 36 to 46% (mean 41%)
    2. Age >18 years: 36 to 44% (mean 41%)
  9. Male
    1. Age 12-18 years: 37 to 49% (mean 43%)
    2. Age >18 years: 41 to 50% (mean 47%)
  • Anemia Cutoffs
  1. Men
    1. Age 12-14 years: <37.3%
    2. Age 15-17 years: <39.7%
    3. Age >17 years: <38% (WHO) or <39.9% (CDC)
  2. Women (Non-pregnant, non-lactating)
    1. Age 12-14 years: <35.7%
    2. Age 15-17 years: <35.9%
    3. Age >17 years <35% (WHO) or <35.7% (CDC)
  3. Women in Pregnancy (CDC Guidelines <5th percentile)
    1. First Trimester: <33.0%
    2. Second Trimester: <32.0%
    3. Third Trimester: <33.0%
  4. Children (CDC Guidelines <5th percentile)
    1. Age 1-2 years: <32.9%
    2. Age 2-5 years: <33.0%
    3. Age 5-8 years: <34.5%
    4. Age 8-11 years: <35.4%
  5. Infants (2 S.D. below mean)
    1. Term (cord blood): <42% (mean 51%)
    2. Newborn (1-3 days): <56 (mean 45%)
    3. Age 2 weeks: <53% (mean 41%)
    4. Age 1 month: <44% (mean 33%)
    5. Age 2 months: <35%(mean 28%)
    6. Age 6 months: <36% (mean 31%)
    7. Reference
      1. Shilkofski (2005) Harriet Lane Handbook, 17th ed, Mosby, p. 337
  • Increased Hematocrit
  1. Erythrocytosis
    1. Dehydration
  2. Profound diuresis
  3. Hemoconcentration
    1. Burn Injury
    2. Trauma
    3. Shock
  4. Polycythemia Vera
  5. High Altitude
  • Decreased Hematocrit
  1. See Anemia
  2. Plasma Volume expansion with constant RBC mass
    1. Pregnancy
  3. Recovery stage after Acute Hemorrhage
    1. Hematocrit lags blood loss (not reliable indicator)
  • References
  1. Behrman (2000) Nelson Pediatrics, Saunders, p. 1462
  2. Johnson (1993) Harriet Lane Handbook, Mosby, p. 231
  3. (1998) MMWR Morb Mortal Wkly Rep 47:1-29 [PubMed]
    1. http://www.cdc.gov/mmwr/pdf/rr/rr4703.pdf