Measurement of prostate-specific antigen by use of a novel blood collection and analytical system

Prostate-specific antigen (PSA) is widely used in the detection and monitoring of prostate cancer. We developed a system for the self-collection and transport of capillary whole blood for PSA analysis, with the goal of reducing phlebotomy visits and, thus, increasing the access and utilization of PSA in prostate cancer screening and monitoring.

The blood collection device [BIOSAFE Blood Transport System (BTS] collects 70 microL of blood through a heparin-coated material into 200 microL of stabilizing solution. The diluted whole blood is used for measurement of PSA by a modified version of the Hybritech Tandem-MP PSA Assay. Results were compared for matched samples of professionally and self-collected BTS blood and for matched BTS samples sera from blood collected by venipuncture. Imprecision for the whole-blood PSA measurement was estimated from analysis of whole-blood controls in duplicate, twice per day, over 20 days.

BTS samples (n = 140) collected by a qualified healthcare professional compared with serum samples yielded the regression equation: y =1.02x + 0.04 (S(yx) = 0.35; r = 0.99). Comparison of the results for samples (n = 128) collected by the patient without professional assistance with serum samples yielded: y = 1.08x + 0.02 (S(yx) = 0.31; r = 0.99). The between-run CVs at 0.069, 0.53, 2.9, and 10.7 microg/L were 21%, 6.0%, 3.5%, and 3.8%, respectively. PSA was stable in BTS samples stored for 21 days at 18-24 degrees C and for 7 days at 37 degrees C.

The BIOSAFE BTS system allows accurate and convenient measurement of circulating PSA by a precise method for diluted whole blood.