title: Physiologic (intraindividual) variation of serum prostate-specific antigen in 814 men from a screening population.
abstract: OBJECTIVE
  We measured the intraindividual variation of prostate-specific antigen (PSA) in the serum of healthy men screened for prostate cancer.
  
  
  METHODS
  We used a fully automated PSA assay system (ACS: 180 assay) to evaluate a screening population of 814 men (mean age, 63.3 years; range, 50 to 79 years) without documented prostate cancer or prostate surgery. A second blood sample was drawn 15 to 183 days after the first specimen (mean, 80 days).
  
  
  RESULTS
  In the ACS PSA ranges of 0 to 7.2 ng/mL, 7.3 to 17.9 ng/mL, and 18.0 ng/mL or greater (O to 4 ng/mL, 4 to 10 ng/mL, and 10.0 ng/mL or greater by the Tandem-R assay), the mean coefficient of variation of the first and second blood drawn was 20%, 12%, and 10%, respectively. In 435 men whose first blood samples were measured twice for PSA difference (interassay or run-to-run variation), the intraindividual variation in the range of 0 to 7.2 ng/mL was significantly larger than the interassay variation, which was also true the 7.3 to 17.9 ng/mL range. In the range of 0 to 7.2 ng/mL, 251 of 695 (36%) showed a 20% or greater relative increase and 69 of 695 (10%) showed a 1.3 ng/mL (0.75 ng/mL by the Tandem-R assay) or greater absolute increase of PSA at the second blood sample.
  
  
  CONCLUSIONS
  We conclude that in the low ranges of PSA concentrations, one should consider the possibility of substantial intraindividual variation when interpreting serial PSA measurements.
authors.affiliation: Department of Urology, Stanford University School of Medicine, California, USA.
authors.forename: K
authors.initials: K
authors.lastname: Komatsu
authors.forename: N
authors.initials: N
authors.lastname: Wehner
authors.forename: A F
authors.initials: AF
authors.lastname: Prestigiacomo
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.forename: T A
authors.initials: TA
authors.lastname: Stamey
mesh_terms: D000368:Aged; D006801:Humans; D007118:Immunoassay; D015592:Immunoradiometric Assay; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000517:prevention & control*; D012016:Reference Values
chemical_list: D017430:Prostate-Specific Antigen