title: Prevalence of neutropenia in the U.S. population: age, sex, smoking status, and ethnic differences.
abstract: BACKGROUND
  Benign reductions in neutrophil counts may be more common at certain ages and in certain ethnic groups and may be affected by sex and smoking status.
  
  
  OBJECTIVE
  To determine differences in neutrophil counts in the U.S. population according to ethnicity, age, sex, and smoking status.
  
  
  METHODS
  Population-based, cross-sectional study.
  
  
  METHODS
  Various locations in the United States.
  
  
  METHODS
  25,222 participants in the 1999 to 2004 National Health and Nutrition Examination Survey who were 1 year of age or older.
  
  
  METHODS
  Complete blood counts and comparison of means and the proportion of participants with neutropenia.
  
  
  RESULTS
  Relative to white participants, black participants had lower leukocyte counts (mean difference, 0.89 x 10(9) cells/L; P < 0.001), lower neutrophil counts (0.83 x 10(9) cells/L; P < 0.001), and similar lymphocyte counts (0.022 x 10(9) cells/L; P = 0.36), whereas Mexican-American participants had slightly higher mean leukocyte counts (0.16 x 10(9) cells/L; P = 0.014), higher neutrophil counts (0.11 x 10(9) cells/L; P = 0.026), and higher lymphocyte counts (0.095 x 10(9) cells/L; P < 0.001). The prevalence of neutropenia (neutrophil count <1.5 x 10(9) cells/L) was 4.5% among black participants, 0.79% among white participants, and 0.38% among Mexican-American participants. The prevalence of neutropenia was higher among males and children younger than 5 years of age. Neutrophil counts less than 1.0 x 10(9) cells/L were observed in fewer than 1% of the overall sample (0.57% in black participants, 0.11% in white participants, and 0.08% in Mexican-American participants). Smoking was associated with higher leukocyte and neutrophil counts but had a smaller effect among black and Mexican-American participants than among white participants.
  
  
  CONCLUSIONS
  Because estimates are based on single measures, fluctuations over time could not be determined.
  
  
  CONCLUSIONS
  In the United States, neutrophil counts are lower in black persons than in white persons and neutropenia is more prevalent in black persons. Neutrophil counts are slightly higher in Mexican-American persons than in white persons, and neutropenia is uncommon in both groups. The clinical implications of these findings are unclear, but they suggest that when determining the need for a diagnostic evaluation for neutropenia, clinicians should consider the patient's age, sex, ethnicity, and smoking status.
authors.affiliation: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Hsieh
authors.forename: James E
authors.initials: JE
authors.lastname: Everhart
authors.forename: Danita D
authors.initials: DD
authors.lastname: Byrd-Holt
authors.forename: John F
authors.initials: JF
authors.lastname: Tisdale
authors.forename: Griffin P
authors.initials: GP
authors.lastname: Rodgers
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D044383:Black People / Q000706:statistics & numerical data; D001772:Blood Cell Count; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data; D008875:Middle Aged; D009503:Neutropenia / Q000208:ethnology*; D015995:Prevalence; D017678:Sex Distribution; D012907:Smoking / Q000208:ethnology*; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data; D001741:Black or African American