Intraindividual variations of total and percent free serum prostatic-specific antigen levels in patients with normal digital rectal examination.
OBJECTIVE
To analyze intraindividual variations of total and percent free serum prostate-specific antigen (PSA) in patients with normal digital rectal examination.


METHODS
Total and free serum PSA were determined in two blood samples corresponding to 107 nonconsecutive patients. The period between both determinations ranged from 23 to 60 days. Prostatic biopsy was done after both determinations in all except 17 patients because the two serum PSA concentrations were <4 ng/ml. Total and free PSA were determined using double monoclonal antibody immunoassay Tandem and Tandem free (Hybritech Inc.). The diagnosis was benign prostatic hyperplasia (BPH) in 63 patients and prostate cancer (PCA) in 44.


RESULTS
The variations of PSA ranged between -6.8 and +3.2 ng/ml in BPH patients and between -2.8 and +9.0 in patients with PCA. The median coefficients of variation were 15.4 and 15.7% respectively. The variations in the percent free PSA were between -30.7 and +40.9 in the BPH group and between -17.9 and +15.8 in the PCA group. The median coefficients of variation were 32.2 and 32.3% respectively. If prostatic biopsy had been indicated when percent free PSA had been </=25 in the PSA range of 4.1-10 ng/ml, we would have found discrepancies in 15% of all the patients. The sensitivity for the first determination would have been 100 and 94.4% for the second. The rate of negative biopsies would have been reduced by 16.6 and 19. 4% respectively.


CONCLUSIONS
Intraindividual variations in serum PSA concentration and percent free PSA could have clinical implications in the decision to perform prostatic biopsy.
Department of Urology, Vall d'Hebron Hospital, Autònoma University, Barcelona, Spain.
J
J
Morote
C X
CX
Raventós
J A
JA
Lorente
G
G
Enbabo
M
M
López
I
I
de Torres
D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010173:Palpation; D011467:Prostate / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000175:diagnosis; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D012007:Rectum; D012680:Sensitivity and Specificity
D017430:Prostate-Specific Antigen