Race-specific WBC and neutrophil count reference intervals.

Healthy African Americans are known to have reduced white blood cell counts (WBC) and absolute neutrophil counts (ANC) compared with European Americans, with little agreement about the levels in reference intervals. The objective is to establish race-specific reference intervals for WBC and ANC using US National Health and Nutrition Examination Survey (NHANES) of 2000-2003. A total of 14,184 civilian noninstitutionalized US citizens participated in NHANES 2000-2003 had complete blood count, red cell distribution width, platelet count and automated WBC differential determined on a Coulter MAXM. The exclusion criteria were used: ferritin <12 ng/ml, pregnancy, body mass index >30, diastolic blood pressure >100 mm Hg, creatinine >2.5 mg/dl, glucose >126 mg/dl. Data were separated into six sex/race categories: female non-Hispanic white, non-Hispanic black (NHBF)], Mexican American; male non-Hispanic white, non-Hispanic black (NHBM), Mexican American and two age groupings (12-18 and >18 years). NHB 2.5-97.5 percentile WBC and (ANC) limits follow (units: × 10⁹ /l): NHBM, ages 12-18: 3.2-9.3 (1.0-6.2); NHBF, ages 12-18: 3.7-10.1 (1.2-6.6); adult NHBM: 3.1-9.9 (1.3-6.6); adult NHBF: 3.4-11 (1.4-7.5). NHB limits are significantly lower than the NHW and MA limits. In most US healthcare organizations, insufficient agreement exists because of large differences in reference intervals for different ethnicities. In areas with peoples of African descent (>10--20%), race-specific WBC and ANC reference intervals must be provided for proper diagnosis and clinical research.