The effects of chlorhexidine-based preservative tubes on routine urinalysis stability

INTRODUCTION: To evaluate the effects of chlorhexidine-based preservative tubes on analytes for routine urinalysis.
METHODS: Urine specimen (n=84) aliquots in polystyrene tubes (PS) with no additives (Fýratmed Co. Ltd., Istanbul, Turkey) and in Becton–Dickinson Vacutainer® Plus Urinalysis Preservative (BD-UAP) tubes (Becton Dickinson Inc., NJ, USA) were analyzed on automatic modular urine analyzer (Dirui Industry, Changchun, China) and the results were compared. Stability was assessed by re-analyzing urine samples in BD-UAP tubes after three and six hours of storage and comparing with initial results. Cohen’s kappa coefficient (κ) was calculated to assess the agreement of results.
RESULTS: Squamous epithelial cell and pH agreement between the tubes was moderate (κ=0.60 and 0.58, respectively). Bilirubin, ketone, protein, nitrite, and glucose showed perfect agreement with the PS tube and remained stable for up to six hours in the BD-UAP tube (κ=1.00, 0.92, 0.83, 0.93, 1.00, respectively). Red blood cells, white blood cells, bacteria, blood, and leukocyte esterase showed moderate to substantial stability at six hours (κ=0.56, 0.77, 0.76, 0.87, 0.57, respectively).
DISCUSSION AND CONCLUSION: Although storage in chlorhexidine-based preservative tubes has limited effects on chemical strip analysis, these tubes may not be considered optimal for microscopic examination.