Variations in prostate-specific antigen free/total ratio in acute stress.
Serum prostate-specific antigen complexed to alpha2-macroglobulin is occult and is not detected by conventional immunoassays. Conditions affecting alpha2-macroglobulin levels may alter the specificity of prostate-specific antigen free/total ratio in predicting prostate cancer. A group of patients (n=24) undergoing surgical stress due to a coronary artery bypass grafting was followed pre- and postoperatively up to 6 days. Total and free prostate-specific antigen, alpha2-macroglobulin, and C-reactive protein were measured by electrochemiluminescence, immunonephelometry, and immunoturbidimetry, respectively. Total prostate-specific antigen and C-reactive protein increased significantly postsurgery and remained elevated. Free/total ratio correlated negatively with C-reactive protein only (p = 0.000) using xtgee panel data analysis, after correction for plasma volume changes using albumin. Increased C-reactive protein may reflect falsely decreased free/total ratio. Therefore, prostate-specific antigen free/total ratio would be more reliable if interpreted in combination with information about CRP. However, it is recommended to defer the measurement of free/total ratio if CRP is highly elevated.
Department of Pathology and Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon.
Rami A
RA
Mahfouz
Najwa K
NK
Cortas
George
G
Ibrahim
Simon
S
Khalife
Rose T
RT
Daher
D000368:Aged; D002097:C-Reactive Protein / Q000378:metabolism*; D001026:Coronary Artery Bypass; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D013312:Stress, Physiological / Q000502:physiology*; D013514:Surgical Procedures, Operative; D000511:alpha-Macroglobulins / Q000378:metabolism*
D000511:alpha-Macroglobulins; D002097:C-Reactive Protein; D017430:Prostate-Specific Antigen