[Time-resolved-fluoroimmunoassay for the determination of prostate-specific-antigen in capillary-blood spotted on filter paper and its clinical significance in prostate cancer patients].

Prostate-specific-antigen (PSA) has recently become widely recognized as an important tumor marker for prostate cancer. For relieving the examinee from pain and saving the time in blood collection, we developed a new method, based on time-resolved fluoroimmunoassay (TR-FIA), using a dried disc paper to collect capillary-blood. The standard curve ranged from 1.0 to 300 ng/ml, the intraassay (CV% was 4.09 to 6.36 (n = 10), while the interassay CV% was 3.45 to 8.87 (n = 2, k = 7). The diluted linearity and analytical recovery (91.5 to 98.2%) seemed to be satisfactory for routine use. All the samples from 30 healthy male adults had non-detectable serum PSA less than 1.0 ng/ml. When the cut-off value was set at 3.4 ng/ml (MEAN + SD of BPH), the positive rate in prostate cancer cases was 85.7% (12/14), in BPH cases was 20.0% (2/10) and in other benign urological disease was 0.0% (0/20). The clinical sensitivity was 85.7%, the specificity 93.3% and the efficacy 90.9%, accordingly. In conclusion, the newly developed TR-FIA method using dried disc paper to collect capillary-blood was quantitatively suitable as a routine test for prostate cancer, because of its simplicity in blood collection and less invasiveness to the examinee.