Objective: The aim of study was to determine unnecessary repeated total prostate specific antigen(tPSA) according to minimum retest interval and to evaluate the change between consecutive measurement results with RCV.

Material and Methods: According to report of Association for Clinical Biochemistry and Laboratory Medicine, when first result is raised, it is recommended to repeat tPSA once in 6 weeks to assess the trend. tPSA test results which were requested between March 2015 and 2017 in our hospital were evaluated retrospectively. If tPSA was>2.5 ng/mL and this test was repeated in less than 6 weeks, it was determined as unnecessary repeated test. RCV was calculated.

Results: The number of tPSA was 1794 and number of consecutive tPSA requested was 427 (12.5%). The first tPSA result was>2.5 ng/mL in 46.4% (198/427) of consecutive tPSA tests, 49% of these tests(97/198) were unnecessary. RCV was calculated as 51.45%. In 82.5% (80/97) of unnecessary repeated tPSA, the change between two results was smaller than RCV. Number of consecutive tests which changed below RCV was significantly lower in appropriately requested tPSA tests than unnecessary repeated tPSA (p=0,002).

Conclusion: Absence of significant difference between two consecutive results in unnecessary repeated test according to RCV suggests the importance of test requesting according to guidelines. We believe that our work will raise awareness about reducing unnecessary requests.