title: Relationship of demographic and clinical factors to free and total prostate-specific antigen.
abstract: OBJECTIVE
  To characterize the role of demographic and clinical parameters in the measurements of prostate-specific antigen (PSA), free PSA (fPSA), and percent free PSA (%fPSA).
  
  
  METHODS
  This was a cohort study of volunteers to a randomized screening trial. A central laboratory determined PSA and fPSA for the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. A baseline evaluation of free and total PSA was done for 7183 white, black, Asian, Hispanic, and other male volunteers, aged 55 to 74 years. Comparisons were made across racial and ethnic groups and across a set of clinical parameters from a baseline questionnaire.
  
  
  RESULTS
  The median levels of serum PSA were less than 2.1 ng/mL in each age-race grouping of the study participants. The levels of free and total PSA were higher in black (n = 868, 12%) participants than in white (n = 4995, 70%) and Asian (n = 849, 11.8%) participants. Individuals who identified themselves as ethnically Hispanic (n = 339, 4.7%) had median PSA levels higher than whites who were not Hispanic. The free and total PSA levels increased with age, particularly among men 70 to 74 years old. However, the %fPSA levels showed less variation among the four racial groups or by age. The free and total PSA levels were higher among those who had a history of benign prostatic disease.
  
  
  CONCLUSIONS
  Demographic (age and race/ethnicity) and clinical (history of benign prostatic disease) variables had a moderate effect on the measures of PSA and fPSA and very little effect on %fPSA.
authors.affiliation: Lombardi Cancer Center, Georgetown University, Washington, DC 20007-2197, USA.
authors.forename: E P
authors.initials: EP
authors.lastname: Gelmann
authors.forename: D
authors.initials: D
authors.lastname: Chia
authors.forename: P F
authors.initials: PF
authors.lastname: Pinsky
authors.forename: G L
authors.initials: GL
authors.lastname: Andriole
authors.forename: E D
authors.initials: ED
authors.lastname: Crawford
authors.forename: D
authors.initials: D
authors.lastname: Reding
authors.forename: R B
authors.initials: RB
authors.lastname: Hayes
authors.forename: B S
authors.initials: BS
authors.lastname: Kramer
authors.forename: D L
authors.initials: DL
authors.lastname: Woodrum
authors.forename: J K
authors.initials: JK
authors.lastname: Gohagan
authors.forename: D L
authors.initials: DL
authors.lastname: Levin
mesh_terms: D000368:Aged; D044466:Asian People / Q000235:genetics; D044383:Black People / Q000235:genetics; D015331:Cohort Studies; D006630:Hispanic or Latino / Q000235:genetics / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000592:standards*; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood* / Q000235:genetics* / Q000592:standards; D012680:Sensitivity and Specificity; D044465:White People / Q000235:genetics
chemical_list: D017430:Prostate-Specific Antigen