Objective: To illustrate the variability of serum Prostate Specific Antigen (PSA) and its causes in relevant clinical patient populations.
Setting: University Hospital Rotterdam, the Netherlands.
Design: Descriptive.
Methods: Six different methods of PSA analysis were applied to sera of 19 participants of a screening population, 20 patients after radical prostatectomy, and 15 newly diagnosed patients with a prostate carcinoma. The Hybritech Tandem-R value was chosen as the standard to compare the methods of analysis. Around a standard of 4.0 micrograms/l a range of 3.3 to 7.2 micrograms/l was found; around 10.0 micrograms/l a range of 8.7 to 18.5 micrograms/l. After radical prostatectomy the different methods of analysis agreed completely in only 5 out of 15 patients with respect to serum PSA.
Conclusion: Because of a considerable variability in serum PSA values between different laboratories and methods of analysis, and of overlap between benign and malignant prostatic diseases, reference values of PSA should be handled with great care.