title: Serum prostate-specific antigen concentration and hemodilution among Chinese middle-aged obese men: a hematocrit-based equation for plasma volume estimation is induced.
abstract: BACKGROUND
  A hematocrit (HCT)-based and a body surface area (BSA)-based equations were applied for plasma volume (PV) estimation, respectively, to confirm and quantify the hemodilution effect in prostate-specific antigen (PSA) screening among obese men. The agreement between the equations was additionally investigated.
  
  
  METHODS
  A total of 1,444 men were retrospectively collected, with ages 40 to 65 years, PSA 0 to 4 ng/mL, and no prostate cancer. PSA mass was calculated as PSA concentration multiplied by PV. Multivariable linear regression models, theoretical models, and the Bland-Altman method were used.
  
  
  RESULTS
  PSA concentration significantly decreased with increasing body mass index (BMI; β = -0.011, P < 0.001); however, PSA mass estimated by HCT- (β = 0.004, P = 0.132) and BSA (β = -0.003, P = 0.094)-based equations remained consistent. A screening PSA of 4.0 ng/mL in nonobese men was found to be corresponding to 3.32 and 3.68 ng/mL in obese men extrapolated by PV on the basis of HCT and BSA, respectively. Moreover, the mean (95% confidence interval) difference of PV between the two equations was 0.33 (-0.06 to 0.73) L.
  
  
  CONCLUSIONS
  The inverse relationship between PSA concentration and BMI might be explained by a hemodilution effect among obese men. There is significant variation in PV calculated by the two equations.
  
  
  CONCLUSIONS
  A value between 3.32 and 3.68 ng/mL might be recommended for PSA screening in middle-aged obese Asian men.
authors: Medical Department, Taihu Cadre's Sanatorium of Jiangsu Province, Wuxi, Jiangsu Province 214086, China. lifeng19792001@163.com
authors: Feng
authors: F
authors: Li
authors: Zhenhai
authors: Z
authors: Shen
authors: Yun
authors: Y
authors: Lu
authors: Jingting
authors: J
authors: Yun
authors: Yupeng
authors: Y
authors: Fan
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001830:Body Surface Area; D002681:China; D006400:Hematocrit; D006438:Hemodilution; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*; D010953:Plasma Volume; D017430:Prostate-Specific Antigen / Q000097:blood*
chemical_list: D017430:Prostate-Specific Antigen