Relationship between lean body mass and serum renal biomarkers in healthy dogs.
BACKGROUND
Symmetric dimethylarginine (SDMA) is an accurate and precise biomarker for estimating glomerular filtration rate (GFR) in humans and cats. Serum creatinine (sCr) also correlates with GFR, but has limitations as a biomarker of renal function because nonrenal factors can influence its concentration.


OBJECTIVE
Differences in lean body mass (LBM) influence sCr, but not serum SDMA concentrations.


METHODS
Forty-one healthy Beagles, mean age 9.9 years (range: 3.1-14.8 years), were studied over a 6 month period.


METHODS
Serum biomarkers of renal function were measured prospectively at baseline, and 1, 3, and 6 months. SDMA concentrations were measured by liquid chromatography-mass spectroscopy and sCr concentrations by enzymatic colorimetry. Body composition was determined by dual energy x-ray absorptiometry.


RESULTS
LBM (P < .001) and age (P = .006) were significant explanatory variables for sCr concentration (R(2) = 0.38), but not SDMA concentration. Time on food was the only significant explanatory variable for SDMA concentration (R(2) = 0.49). SDMA concentrations decreased across time (P < .001). LBM was affected by sex (males > females; P = .02). Mature adult dogs (<8 years) had greater LBM compared with geriatric dogs (≥8 years; P < .001).


CONCLUSIONS
sCr concentrations, but not SDMA concentrations, are influenced by LBM, which limits sCr utility as a biomarker for monitoring renal function in dogs with decreased LBM. Reductions in LBM can lower sCr concentration and overestimate GFR. SDMA concentrations, but not sCr concentrations were influenced by time on food. SDMA could have clinical advantages over sCr in monitoring response to nutritional interventions.
Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR, 97331-4802.
Jean A
JA
Hall
IDEXX Biotechnology Group, IDEXX Laboratories, Inc., Westbrook, ME, 04092.
Maha
M
Yerramilli
IDEXX Biotechnology Group, IDEXX Laboratories, Inc., Westbrook, ME, 04092.
Edward
E
Obare
IDEXX Biotechnology Group, IDEXX Laboratories, Inc., Westbrook, ME, 04092.
Murthy
M
Yerramilli
Pet Nutrition Center, Hill's Pet Nutrition, Inc., Topeka, KS, 66617-1587.
Lynda D
LD
Melendez
Pet Nutrition Center, Hill's Pet Nutrition, Inc., Topeka, KS, 66617-1587.
Dennis E
DE
Jewell
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001823:Body Composition / Q000502:physiology; D004285:Dogs / Q000033:anatomy & histology / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000662:veterinary; D007668:Kidney / Q000502:physiology; D008297:Male
D015415:Biomarkers; C024917:symmetric dimethylarginine; D001120:Arginine
Canine; Creatinine; Symmetric dimethylarginine; Urea nitrogen