Symmetric dimethylarginine concentrations in dogs with hypothyroidism before and after treatement with levothyroxine.

OBJECTIVES To evaluate the serum symmetric dimethylarginine (SDMA) and serum creatinine concentrations in a population of hypothyroid dogs at the time of diagnosis and after treatment. MATERIALS AND METHODS Serum SDMA and serum creatinine were measured in serum samples of 24 healthy dogs and 24 hypothyroid dogs, at the time of diagnosis (T0) and after supplementation with levothyroxine (T1). RESULTS The mean SDMA concentrations (reference intervals [RI] 1.4 mg/dL). In all but one dog, serum creatinine normalised after treatment. CLINICAL SIGNIFICANCE The SDMA and serum creatinine concentrations were higher in hypothyroid dogs at diagnosis as compared to healthy dogs. Serum creatinine concentrations were increased in one-third of the hypothyroid dogs and in the majority of cases normalised after levothyroxine supplementation. SDMA concentrations were rarely above the upper limit of the RI when the higest (<18 μg/dL) cut-off was employed. The diagnostic accuracy of SDMA in dogs with thyroid dysfunction requires additional evaluation.