Symmetric dimethylarginine and renal function analysis in horses with dehydration

Abstract

Background: Acute dehydration caused by a variety of diseases in horses can lead to acute kidney injury. However, current renal biomarkers usually indicate renal damage late in the course of the disease. A novel biomarker would be helpful to diagnose renal disease earlier.Objectives: 1) To estimate the correlation of serum symmetric dimethylarginine (SDMA) concentrations with the degree of dehydration, traditional renal biomarkers and renal function analysis, and 2) to determine the value of SDMA as a prognostic and early biomarker of renal injury in horses. Study design: Prospective cohort.Methods: Serum SDMA, creatinine and urea concentrations and renal function analysis were measured in 41 horses with dehydration at four time points until 48 hours after admission. Horses were grouped according to their dehydration level into mildly, moderately and severely dehydrated groups.Results: Serum SDMA concentrations at admission correlated with creatinine concentrations (r = 0.412, P<0.001). Differences of SDMA concentrations at admission were detected among dehydration levels but not between survivors and non-survivors. Significant correlations of SDMA concentrations with other markers of renal function analysis and short-term outcome were not observed. Main limitations:Besides the small sample size and low statistical power, missing urine samples at specific time points were also one of the main limitations. Only one of the horses developed acute kidney injury, which made the evaluation of the predictive value of SDMA difficult.Conclusions: SDMA concentrations correlated significantly with creatinine concentrations in dehydrated horses. Further research is needed to reveal the application of SDMA in horse.

Biomarkers of Kidney Disease in Horses: A Review of the Current Literature

“…Similar to SDMA in other species, factors that impact GFR also influence SDMA [ 12 ]. This has been confirmed by elevated SDMA in dehydrated horses [ 19 ] and in exercising endurance horses [ 13 ].…”

“…These showed different serum concentrations of SDMA between (1) healthy horses versus horses with AKI [ 18 , 19 ], (2) horses with different levels of dehydration [ 19 ], and (3) endurance horses before versus after the race, with post-race SDMA concentrations being higher with longer racing distance [ 13 ]. There was no difference in serum SDMA concentrations between healthy horses versus horses with cardiac disease [ 14 ], or between survivors and non-survivors with different degrees of dehydration (lower SDMA concentrations were found in survivors than in non-survivors, however this was not statistically different) [ 19 ]. SDMA concentrations have only been reported on very few equine AKI cases (37 cases divided over 4 studies) [ 15 , 16 , 18 , 19 ], and so far on no confirmed equine CKD cases.…”

“…There was no difference in serum SDMA concentrations between healthy horses versus horses with cardiac disease [ 14 ], or between survivors and non-survivors with different degrees of dehydration (lower SDMA concentrations were found in survivors than in non-survivors, however this was not statistically different) [ 19 ]. SDMA concentrations have only been reported on very few equine AKI cases (37 cases divided over 4 studies) [ 15 , 16 , 18 , 19 ], and so far on no confirmed equine CKD cases. One study did not identify different SDMA concentrations between healthy horses and horses at risk for AKI (and therefore potential early AKI), whereas some traditional markers (urinary protein and urine protein to creatinine ratio (UP/UC) and urinary GGT/creatinine ratio) differed [ 18 ].…”

“…One study did not identify different SDMA concentrations between healthy horses and horses at risk for AKI (and therefore potential early AKI), whereas some traditional markers (urinary protein and urine protein to creatinine ratio (UP/UC) and urinary GGT/creatinine ratio) differed [ 18 ]. Two other studies reported 2 and 7 cases with elevated SDMA but normal creatinine; these cases were interpreted as potential yet unconfirmed subclinical AKI or CKD cases [ 15 , 19 ]. Therefore, similar as to small animals, there is a possibility that SDMA is beneficial to detect early equine AKI cases, when creatinine is still within reference range, yet evidence is currently lacking.…”

Neutrophil gelatinase-associated lipocalin in dehydrated horses: A prospective case-control study

“…Blood urea nitrogen (BUN) has no direct linear correlation with GFR and is also affected by factors such as diet and liver function [9]. In a previous study investigating symmetric dimethylarginine (SDMA), which is also a novel renal biomarker, we described a correlation between serum SDMA concentration and creatinine: a signi cant correlation was found and SDMA at admission differed among dehydration levels, but the distribution of SDMA in the 3 groups overlapped easily with each other [10]. Further research is still needed to identify the role of SDMA in equine renal disease.Neutrophil gelatinase-associated lipocalin (NGAL) is a protein originally detected in activated neutrophils.…”