title: Revision in reference ranges of peripheral total leukocyte count and differential leukocyte percentages based on a normal serum C-reactive protein level.
abstract: OBJECTIVE
  A higher total leukocyte count is a predictor of all-cause mortality and cardiovascular morbidity. The currently used reference range for peripheral total leukocyte count is wide (4.5-11.0 x 10(9)/L) and is associated with a low sensitivity in identifying non-infectious chronic diseases. We attempt to revise it based on a normal serum C-reactive protein (CRP) level.
  
  
  METHODS
  Study subjects were participants in a health check program at our hospital between 2000 and 2002. Those whose leukocyte analysis had been checked with the Sysmex Cell Counter NE-9000 were enrolled.
  
  
  RESULTS
  Significantly positive relationships between CRP level and total leukocyte count, neutrophil percentage, and monocyte percentage were found in all subjects (n = 14,114; p < 0.0001). In contrast, CRP level had a significantly inverse correlation with lymphocyte percentage (p < 0.0001). A proposed new reference range for total leukocyte count was estimated based on the data in the normal CRP level group (CRP < 0.1 mg/dL; n = 4839). To rest on the essence of statistics that the range of [mean +/- 2 standard deviations] contains approximately the middle 95% of observations in a sampled population, a new reference range for total leukocyte count was accordingly estimated to be 3.11-8.83 x 10(9)/L.
  
  
  CONCLUSIONS
  In view of the abundant evidence showing that a higher peripheral total leukocyte count is harmful to health, a down-correction of its upper reference range from the currently used 11.0 x 10(9)/L to the proposed 8.83 x 10(9)/L, based on a normal CRP level, should allow more abnormal health conditions to be identified and promote the usefulness of peripheral leukocyte analysis.
authors: Department of Internal Medicine, College of Medicine and Hospital, National Taiwan University, Taipei, Taiwan.
authors: Zei-Shung
authors: ZS
authors: Huang
authors: Shyh-Chyi
authors: SC
authors: Lo
authors: Woei
authors: W
authors: Tsay
authors: Kwan-Lih
authors: KL
authors: Hsu
authors: Fu-Tien
authors: FT
authors: Chiang
mesh_terms: D002097:C-Reactive Protein / Q000032:analysis*; D006801:Humans; D007958:Leukocyte Count / Q000592:standards*; D012016:Reference Values
chemical_list: D002097:C-Reactive Protein