Validation of a spectrophotometric method for GGT measurement in canine urine and determination of the urine GGT-to-creatinine ratio reference interval and biological variation in 41 healthy dogs

Abstract

The urine gamma-glutamyl transferase (GGT)-to-creatinine ratio has been used to monitor patients at risk of acute renal injury. We validated the spectrophotometric quantification of GGT in urine in a commercial biochemistry analyzer.The assay was precise, accurate, and linear. Intra-assay precision was 3.59% in 4 samples, with GGT concentrations of 47-195 U/L. Inter-assay precision in 3 samples with activities of 11-51 U/L was 7.74%. Accuracy was 97.3%, with an absolute bias of 2.7 U/L. Urine GGT was unaffected by hematuria, hemoglobinuria, or bacteriuria. Urine GGT was stable at 20°C and 4°C for up to 3 d. Storage by freezing at −20°C resulted in a significant reduction in enzyme activity. A pH outside the range of 6.5-8 resulted in reduced GGT activity. The biological variation of urine GGT-to-creatinine ratio provided an index of individuality of 1.6, indicating that a population-based reference interval (RI) can be used. The reference change value was calculated, and an increase in consecutive measurements >43% is required to be regarded as significant. The urine GGT-tocreatinine ratio RI obtained in a population of 41 healthy dogs was 8.5-28.5 U/g.

Serial Serum Creatinine and Urinary Acute Kidney Injury Biomarker Measurements in Dogs Envenomated by the European Adder (Vipera Berus).

“…Evidence suggests that uALb/uCr and uNGAL/uCr values are unlikely to be signi cantly affected by microscopic haematuria and haemoglobinuria, respectively (52). Likewise, haematuria and haemoglobinuria are unlikely to signi cantly affect uGGT/uCr (37,38), but it is unknown to what extent results for the other biomarkers in this study might be affected. Although the extent to which myoglobinuria might interfere with biomarker measurement is unknown, it is thought unlikely to in uence the overall conclusions of this study since this was observed only in one dog.…”

“…There are several possible explanations for a lack of increase in uALP in our study compared to others. Poor assay sensitivity might be considered most likely, but differences in timing and storage of samples are also possible explanations (38). An optimal uALP detection window of less than 12 hours after renal insult is reported in humans (39); thus, the detection window may have been missed in our study.…”

Potential Acute Renal Injury in Sheep with Bluetongue Serotype 4

“…GGT is a transferase enzyme present in the cell membranes of various tissues [29]. In kidneys, GGT releases in the renal tubular lumen after injury of the microvilli of the luminal surface of renal tubular epithelial cells [30].…”

Serial serum creatinine, SDMA and urinary acute kidney injury biomarker measurements in dogs envenomated by the European adder (Vipera berus)

“…There are several possible explanations for a lack of increase in uALP in our study compared to others. Poor assay sensitivity might be considered most likely, but differences in timing and storage of samples are also possible explanations [ 38 ]. An optimal uALP detection window of less than 12 h after renal insult is reported in humans [ 39 ]; thus, the detection window may have been missed in our study.…”

“…Evidence suggests that uALb/uCr and uNGAL/uCr values are unlikely to be significantly affected by microscopic haematuria and haemoglobinuria, respectively [ 52 ]. Likewise, haematuria and haemoglobinuria are unlikely to significantly affect uGGT/uCr [ 37 , 38 ], but it is unknown to what extent results for the other biomarkers in this study might be affected. Although the extent to which myoglobinuria might interfere with biomarker measurement is unknown, it is thought unlikely to influence the overall conclusions of this study since this was observed only in one dog.…”