Objective: Information about pre-analytical preparation for urine cystatin C measurement is often contradictory; verification of cystatin C stability in urine samples. Methods: Each urine sample collected from 15 individuals was divided into 4 parts and 3 parts were treated with various stabilizers: 1-sample without stabilizer; 2-sample stabilized with Tencer reagent; 3-sample stabilized with reagent according to our own design (thimerosal-anitimicrobial agent; benzamidin-serine proteases inhibitor; aminocapronic acid-lysine proteases inhibitor, citrate buffer-modulator of pH value; BSA-suppressor of non-specific adsorption and protective colloid effect); 4-sample stabilized with StabilZyme Select. All parts were further divided into 3 aliquots and frozen at -80 °C, or treated by 5 cycles of freezing and thawing, or incubated at room temperature for 15 days. Cystatin C was subsequently determined in all samples. Results: We did not observe any significant change in samples after 5 cycles of freezing and thawing, or incubation at room temperature in samples without as well with stabilizing agent. However, storage at room temperature led to a nonsignificant reduction in cystatin C level by 13% in samples without stabiliser, by 18% with Tencer stabilizer, by 13% with our own designed stabilizer, and by 3% with StabilZyme. Conclusion: Urine samples may be frozen at -80 °C without lost of cystatin C level in that kind of sample and it may be a convenient pre-analytical precaution. Application of Tencer or other tested stabilizers does not significantly improve sample handling.

        Key words: cystatin C, urine, preanalytical conditions, stability.