Measurement serum level of PSA in fresh and freezed blood samples

Prostate specific antigen (PSA) is a useful tumor marker in diagnosis، staging، monitoring and determining the recurrence prostate cancer. This study was design to compare the serum level of PSA in fresh and frozen (at -20C for 72 hrs) blood samples. 111 Patients referring to the urology clinic of Imam Reza hospital، having voiding symptoms، and in need of testing their PSA serum level were selected as the study population. For these patients the PSA was measured stimulataneously in fresh and frozen (at -20C for 72 hrs) blood samples in two independent labs. Then data analyzed using SPSS soft ware. In two labs، there was not any significant difference between the levels of PSA (in fresh and frozen blood sample (P>0. 05). Significant correlation was found between the level of Free PSA (P=0. 001). Besides، significant difference was observed between FPSA/PSA ratio in fresh and frozen samples (P=0. 01). Using of frozen blood samples is useful instead of fresh blood samples in evaluation PSA but not for Free PSA.