Urine specific gravity as an indicator for the determination of urinary GGT in dogs with visceral leishmaniasis

The urinary Gama-Glutamyl Transpeptidase to urinary Creatinine ratio (uGGT/uCR) is a laboratory marker that may signal renal tubular lesion in dogs with visceral leishmaniasis (VL). In this study, our goal was to determine whether urine specific gravity (USG) can accurately indicate an elevated uGGT/uCR and, consequently, tubular injury. Twenty-eight animals with VL and five healthy animals (control group) were included in the study. The diseased animals were classified as azotemic (n = 6) and non-azotemic (n = 22). The difference between all groups was tested with the Kruskal-Wallis test for the USG, uGGT/uCR, and urine protein: creatinine ratio (UPC). Sensitivity, specificity, positive and negative predictive value and the accuracy of using USG as an indicator of tubular injury were calculated with the Receiver Operating Characteristic (ROC curve). The probability of an animal with suboptimal USG presenting tubular injury was obtained by calculating the prevalence ratio. The Kruskal-Wallis test revealed differences between groups for all analyzed parameters (p< 0.05). The chosen USG cut-off value, determined by the ROC curve was 1.030, with an accuracy of 78.09%. The probability of a dog with LV and USG below 1.030 having a high uGGT/uCR ratio was 4.95 (p <0.01, 95% CI - 1.32-18.48) when compared to individuals with ideal DU. In conclusion, dogs positive for Leishmania sp. with low USG (<1.030) should have their uGGT/uCR ratio measured to verify the presence of tubular injury even before the onset of azotemia.