title: Effect of body mass index on serum prostate-specific antigen levels among patients presenting with lower urinary tract symptoms.
abstract: OBJECTIVE
  Studies among asymptomatic male subjects have suggested that a higher body mass index (BMI) is associated with lower serum prostate-specific antigen (PSA) levels. We aimed to investigate whether a similar effect also occurs in patients presenting with lower urinary tract symptoms (LUTS) to a urological unit and its potential implications.
  
  
  METHODS
  A retrospective review was carried out at our centre between 2005 and 2009. The serum PSA and BMI of the patients were retrieved from a prospectively collected database. The BMI was divided into normal (< 23 kg/m2), overweight (23-27 kg/m2), and obese (>27 kg/m2) categories according to WHO recommendation for analysis of the association with PSA level.
  
  
  RESULTS
  A total of 1,612 patients with a mean age of 64.6 were included. The mean PSA levels for the normal, overweight, and obese patients were 4.84, 4.54, and 3.95 ng/ml, respectively, with a significant negative correlation (Spearman's coefficient=-0.05, p=0.03). A significant negative association between PSA and BMI among the normal, overweight, and obese groups was also demonstrated by analysis of variance (p=0.01). After adjusting for age differences, there was a significant difference between PSA level for obese patients with a BMI>27 (3.95 ng/ml) and non-obese patients with a BMI<27 (4.67 ng/ml) with analysis of covariance (p=0.02).
  
  
  CONCLUSIONS
  In symptomatic male patients, a higher BMI was significantly associated with lower PSA levels. BMI should be considered in the interpretation of serum PSA levels in overweight and obese patients presenting with LUTS.
authors.affiliation: Division of Urology, Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Peter Ka-Fung
authors.initials: PK
authors.lastname: Chiu
authors.forename: Annie Yim-Fong
authors.initials: AY
authors.lastname: Wong
authors.forename: See-Ming
authors.initials: SM
authors.lastname: Hou
authors.forename: Sidney Kam-Hung
authors.initials: SK
authors.lastname: Yip
authors.forename: Chi-Fai
authors.initials: CF
authors.lastname: Ng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D006801:Humans; D059411:Lower Urinary Tract Symptoms / Q000097:blood* / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications / Q000503:physiopathology; D050177:Overweight / Q000097:blood / Q000150:complications / Q000503:physiopathology; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D012189:Retrospective Studies
chemical_list: D017430:Prostate-Specific Antigen