An evaluation of four methods of measuring free/ total PSA ratio in patients with and without prostate cancer

A. Das-Gupta*, J. Beaman, S. Brookes, P. Astley, D. A. Gillatt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Introduction: At least nine different manufacturers currently produce at least 14 different methods for measuring total PSA. The number of available methods of measuring the free to total ratio of PSA (f/tPSA) is in turn rapidly expanding. Patients and methods: The f/tPSA was measured in 103 men aged over 50 years immediately before guided sextant prostatic biopsy and the serum f/tPSA compared using four available immunofluorometric assays (Chiron ACS 180. Wallac Déifia Prostatus. Hybritech Tandem-R and DPC Immulite). Results: There were no significant differences between the Déifia Prostatus and Hybritech Tandem-R or between the DPC Immulite and ACS 180 methods in the 71 patients found histologically to have cancer, or the 32 found to have benign prostatic disease. However, there was a highly significant difference between the results of the Déifia Prostatus and both the Chiron ACS 180 and Immulite methods for both benign disease (P< 0.001) and cancer (P < 0.001 ). Differences were also significant between the Hybritech Tandem-R and the Chiron ACS 180 methods (benign; P< 0.02; malignant P < 0.007) and between the Hybritech Tandem-R and DPC Immulite assays for malignant disease only (P< 0.001). There was a significant difference between the last two methods for benign disease (P < 0.05). The accuracy of cancer prediction also varied with the method and threshold selected. There was a correlation between Gleason grade and f/tPSA. Conclusions: With the rapid expansion of f/tPSA testing, we would advise caution in interpreting the results of this measurement and in particular suggest that the details of the method used to obtain the result are reported.

Original languageEnglish
Pages (from-to)13
Number of pages1
JournalBritish Journal of Urology
Issue numberSUPPL. 4
Publication statusPublished - 1998
Externally publishedYes


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