title: Should prostate specific antigen be adjusted for body mass index? Data from the Baltimore Longitudinal Study of Aging.
abstract: OBJECTIVE
  Obesity may be associated with lower prostate specific antigen through hemodilution. We examined the relationship between body mass index and prostate specific antigen by age in men without prostate cancer in a longitudinal aging study to determine whether prostate specific antigen must be adjusted for body mass index.
  
  
  METHODS
  The study population included 994 men (4,937 observations) without prostate cancer in the Baltimore Longitudinal Study of Aging. Mixed effects models were used to examine the relationship between prostate specific antigen and body mass index in kg/m(2) by age. Separate models were explored in men with prostate cancer censored at diagnosis, for percent body fat measurements, for weight changes with time and adjusting for initial prostate size in 483 men (2,523 observations) with pelvic magnetic resonance imaging measurements.
  
  
  RESULTS
  In men without prostate cancer body mass index was not significantly associated with prostate specific antigen after adjusting for age (p = 0.06). A 10-point body mass index increase was associated with a prostate specific antigen difference of -0.03 ng/ml (95% CI -0.40-0.49). Results were similar when men with prostate cancer were included, when percent body fat was substituted for body mass index, and after adjusting for prostate volume. Longitudinal weight changes also had no significant association with prostate specific antigen.
  
  
  CONCLUSIONS
  Consistent with prior studies, we found an inverse relationship between obesity and serum prostate specific antigen. However, the magnitude of the difference was small. Thus, adjusting prostate specific antigen for body mass index does not appear warranted.
authors.affiliation: The James Buchanan Brady Urological Institute, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA. stacyloeb@gmail.com
authors.forename: Stacy
authors.initials: S
authors.lastname: Loeb
authors.forename: H Ballentine
authors.initials: HB
authors.lastname: Carter
authors.forename: Edward M
authors.initials: EM
authors.lastname: Schaeffer
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Anna
authors.initials: A
authors.lastname: Kettermann
authors.forename: E Jeffrey
authors.initials: EJ
authors.lastname: Metter
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D055815:Young Adult
chemical_list: D017430:Prostate-Specific Antigen