Evaluation of ammonia measurements in dogs with two analysers for use in veterinary practice

Abstract

The measurement of ammonia in biological fluids is the only way to diagnose and evaluate hepatic encephalopathy, but samples for ammonia measurement cannot be stored or sent by post. Two analysers for use in veterinary practice have recently become available, the VetTest and the Blood Ammonia Checker II; the reliability of ammonia measurements in canine blood with these two analysers has been evaluated by comparing the results with a standard automated enzymatic assay. Blood samples from 39 dogs, with a range of ammonia concentrations from 5 to 589 microM, were used simultaneously in the three assays. The blood samples were placed immediately on ice, and the measurements were made in duplicate. The intra-assay coefficients of variation were 13.7 per cent for the VetTest, 4.7 per cent for the Blood Ammonia Checker, and 2.8 per cent for the enzymatic assay. The correlation coefficients over the entire range of concentrations were 0.79 between the VetTest and the enzymatic assay, and 0.98 between the Ammonia Checker and the enzymatic assay. The ammonia concentrations recorded in the enzymatic assay were divided into 12 samples within the normal range (0 to 50 microM), 18 samples with moderately increased concentrations (51 to 150 microM), and nine samples with concentrations above 150 microM. No correlation or a poor correlation was found between the results from the VetTest and those from the enzymatic assay from 0 to 50 microM (R = 0.27) and from 50 to 150 microM (R = 0.51; P = 0.05). The results from the VetTest were only reliable in samples with the highest concentrations (R = 0.93; P < 0.05). In contrast, the results from the Ammonia Checker correlated well with the results from the enzymatic assay over all the ranges: R = 0.79 (P < 0.05) from 0 to 50 microM, R = 0.86 (P < 0.05) from 50 to 150 microM, and R = 1.00 (P < 0.05) in samples exceeding 150 microM.

Inherited liver shunts in dogs elucidate pathways regulating embryonic development and clinical disorders of the portal vein

“…This test, however, gives abnormal results for many different liver diseases and is sensitive, but not specific, for congenital and acquired portosystemic shunting (Gerritzen-Bruning et al 2006). Alternatively, screening can be performed by measuring basal plasma ammonia levels (Meyer et al 1995; Sterczer et al 1999; van Steenbeek et al 2009). In Irish wolfhounds, however, a congenital urea cycle enzyme deficiency may also cause hyperammonemia (Zandvliet and Rothuizen 2007).…”

Effect of inflammation on kidney function and pharmacokinetics of COX‐2 selective nonsteroidal anti‐inflammatory drugs rofecoxib and meloxicam

“…Total protein, BUN, and plasma creatinine concentrations were determined with a VetTest 8008 analyzer (Idexx Laboratories Inc, Westbrook, MA, USA) as previously described (Sterczer et al, 1999;Ngure et al, 2000). The analyzer is a dry chemistry system that uses dry reagent slides.…”

Ultrasonographic identification and characterization of congenital portosystemic shunts and portal hypertensive disorders in dogs and cats

“…7,8 Determining the blood ammonia level before performing an abdominal ultrasound examination can greatly increase the positive and negative predictive values of ultrasonography in finding the anomalous vein since chronic hyperammonemia can only be caused by a few diseases such as congenital portosystemic shunts (CPSSs), acquired portosystemic collaterals (APSCs), or urea cycle enzyme deficiency. 7,8 Determining the blood ammonia level before performing an abdominal ultrasound examination can greatly increase the positive and negative predictive values of ultrasonography in finding the anomalous vein since chronic hyperammonemia can only be caused by a few diseases such as congenital portosystemic shunts (CPSSs), acquired portosystemic collaterals (APSCs), or urea cycle enzyme deficiency.…”