Neutropenia

Descriptive text is not available for this imageBASICS

DESCRIPTION

A decrease in the number of circulating neutrophils (both segmented and band forms), strictly defined as an absolute total neutrophil count (ANC) of <1,500/μL in children >1 year of age, <1,000/μL in children <1 year of age, and <5,000/μL in the 1st week of life; in general:

  • Mild neutropenia: ANC 1,000 to 1,500/μL
  • Moderate neutropenia: ANC 500 to 1,000/μL
  • Severe neutropenia: ANC <500/μL
  • To calculate ANC, multiply the total white blood cell (WBC) count by the percentage of segmented neutrophils and band forms.
  • For example: WBC count 5,200/μL with 15% segs/polys, 4% bands, 76% lymphocytes, 5% monocytes: ANC = 5,200 × (0.15 + 0.04) = 988
ALERT

Fever (temperature ≥100.4°F or 38°C) and severe neutropenia is a medical emergency that requires immediate attention including blood culture, broad-spectrum antibiotics, and in most cases, hospital admission.

EPIDEMIOLOGY

  • Normal values for total WBC counts and ANC can vary with age and race.
    • Middle Eastern and African American children can have lower total WBC counts and lower ANCs than their European American peers.
      • The lower normal range for ANC generally does not represent an increased risk for infection in these patients—this is termed benign ethnic neutropenia.
    • Infants have a higher total WBC count and a higher percentage of lymphocytes in their differential counts.
    • Neutropenia is also common in premature or small for gestational age newborns; approximately 6% of these infants have an ANC <1,000/μL; associated with decreased placental blood flow due to hypertension and/or preeclampsia
  • The incidence of neonatal alloimmune neutropenia is 2 per 1,000 live births. The prevalence of congenital and idiopathic neutropenias is 2.1 cases per million in the United States.

ETIOLOGY

  • Decreased production of neutrophils
    • Viral suppression
    • Bone marrow suppression by drugs, chemotherapy, and/or radiation
    • Nutritional deficiencies
    • Primary disorders of myelopoiesis
  • Increased destruction of neutrophils
    • Immune (antibody) mediated
    • Increased use (typically with overwhelming infection)
  • Increased trapping of neutrophils
    • Splenic sequestration

RISK FACTORS

Genetics

A number of mutations causing severe congenital and cyclic neutropenia have been identified.

  • Autosomal recessive: HAX1 (Kostmann syndrome), G6PC3, SBDS (Shwachman-Diamond syndrome)
  • Autosomal dominant: ELANE (can also be a sporadic mutation), GFL1, GATA2, CXCR4 (WHIM syndrome)
  • X-linked: WASP (Wiskott-Aldrich syndrome), TAZ (Barth syndrome)

PATHOPHYSIOLOGY

  • Pathophysiology varies according to the etiology.
  • Causes decreased phagocytic activity due to the decreased number of neutrophils.

There's more to see -- the rest of this topic is available only to subscribers.