[Free/total PSA ratio in clinical and ambulatory application. Are different cutoffs justified?].

Especially in the setting of total prostate-specific antigen (PSA) in the intermediate range of 4-10 ng/ml and a negative digital rectal examination, the use of the free/total (F/T) PSA ratio has proved to be an effective tool in prostate cancer screening. Whole blood should be analyzed as soon as possible after venipuncture to ensure optimal effectiveness of the F/T PSA ratio. If an immediate serum analysis is not possible, the serum should be frozen or stored at a maximum of 4 degrees C for a short period. Otherwise, when applying the F/T PSA cutoffs as recommended in the literature to a cohort with delayed analysis, a lack of specificity arises, and the initial advantage of reducing biopsies is minimized. To prevent loss of quality in a setting with delayed F/T PSA measurement, we recommend that physicians compare their own data critically with presented results and eventually adapt the cutoffs individually.