title: Leukocytosis in obese individuals: possible link in patients with unexplained persistent neutrophilia.
abstract: BACKGROUND
  Recently, it was shown that fat tissue produces and releases inflammatory cytokines, and that obesity may be regarded as a state of low-grade inflammation. In this regard, we aimed to establish an association between obesity and persistent leukocytosis.
  
  
  METHODS
  We present clinical observations of obese subjects primarily referred for further evaluation of leukocytosis without a cause and validated the link between leukocytosis and elevated body mass index (BMI) in a cross-sectional study.
  
  
  RESULTS
  During 1999-2005, 327 patients were referred for further investigation because of persistent leukocytosis. Of these, 15.3% were asymptomatic obese, mostly females, with mild persistent neutrophilia accompanied by elevated acute-phase reactants. After careful evaluation, no recognized cause for leukocytosis was found other than the fact that the patients were obese. During a mean follow-up of 45.6 months, the leukocytosis and the elevated acute-phase reactants persisted and no new causes for leukocytosis were evident. Furthermore, in a cross-sectional analysis of 3716 non-smoker subjects, 62 were found to have leukocytosis. Compared with the population with a normal white blood count range, these subjects with leukocytosis had higher BMI, serum C-reactive protein (CRP) levels, waist circumference, and neutrophil and platelet count (all P < 0.0005). After logistic regression analysis, only BMI was shown to be associated with leukocytosis (P < 0.0005).
  
  
  CONCLUSIONS
  Obesity is recognized as a possible cause for reactive leukocytosis. Awareness of this 'obesity-associated leukocytosis' may help the clinician to avoid more extensive and unnecessary diagnostic work-up, particularly in similar obese subjects.
authors.affiliation: Department of Hematology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. herishanu@yahoo.com
authors.forename: Yair
authors.initials: Y
authors.lastname: Herishanu
authors.forename: Ori
authors.initials: O
authors.lastname: Rogowski
authors.forename: Aaron
authors.initials: A
authors.lastname: Polliack
authors.forename: Rafael
authors.initials: R
authors.lastname: Marilus
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D000368:Aged; D001799:Blood Sedimentation; D015992:Body Mass Index; D002097:C-Reactive Protein; D003430:Cross-Sectional Studies; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation; D007958:Leukocyte Count; D007964:Leukocytosis / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009504:Neutrophils; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D010976:Platelet Count; D012907:Smoking / Q000097:blood; D049629:Waist-Hip Ratio
chemical_list: D016207:Cytokines; D002097:C-Reactive Protein