Semiquantitative glucose measurements in urine samples and urine soaked cat litter

Abstract

Semiquantitative urine glucose measurements are a proposed alternative for the treatment surveillance of unmanageable diabetic cats. The primary objectives of this study were to determine the accuracy of 5 commercially available dipsticks, to re-evaluate a technique for detecting glucosuria in urine-soaked "clumping" type of cat litter described by Schaer and to validate a cat toilet with a sieve bottom. A total of 93 urine samples were analysed using 5 different urine dipsticks. The correlation with a laboratory reference method and the diagnostic accuracy to diagnose pathological glucosuria > 1.48 mmol/l and urinary glucose concentrations ≥ 13.9 mmol/l (therapeutically important cut-off) were determined. Furthermore, the viability of 10 types of cat litter, a cat toilet with sieve bottom, 2 disinfectants, 2 cleaning agents and 2 cat litter deodorants were tested. The correlations of the dipstick results with the reference method were moderate (rSP = 0.633) to good (rSP = 0.846). The sensitivities and specificities to diagnose pathological glucosuria were 0.7-1 and 0.94-1, respectively. Urine glucose concentrations ≥ 13.9 mmol/l were detected with sensitivities of 0.65-1 and specificities of 0.97-1. Four cat litters, one dipstick and a disinfectant containing hydrogen peroxide caused false-positive colour reactions. Depending on the dipsticks and litter used, the measurements from soaked cat litter reduced the urine glucose concentrations by a median of 70-77 %. Pouring the probes into the cat toilet and subsequent measurements from the collecting tank did not falsify the results. Not all urine dipsticks are suitable to monitor insulin therapy in diabetic cats. False positive colour reactions are possible when using dipsticks with high analytical sensitivities, some cat litters and oxidizing disinfectants. Measurements from the collecting tank of the cat toilet are superior to measurements using soaked clumping type of cat litter.