抗甲状腺薬による猫甲状腺機能亢進症治療後の血清対称性ジメチルアルギニン（SDMA）濃度変化

To report changes in serum creatinine and symmetric dimethylarginine (SDMA) concentrations following treatment of feline hyperthyroidism with anti-thyroid medications and compare these biomarkers at baseline between cats that were and were not azotaemic after treatment.

Retrospective study; hyperthyroid cats that were euthyroid (total thyroxine concentration (TT4) 7-40 nmol/L) at 1 month (T1) and/or 2-9 months (T2) following treatment were identified and grouped by renal status defined by serum creatinine concentrations post-treatment. Comparisons were made using non-parametric statistics, and the correlations assessed using Spearman's correlation coefficient. Data are presented as median [minimum-maximum].

Nineteen hyperthyroid cats were included. At baseline, TT4 was negatively correlated with serum concentrations of creatinine (rs = -0.73; P<0.001) but not SDMA (rs = -0.42; P=0.074). Serum creatinine concentrations increased significantly at T1 and T2 (137 [97-241] μmol/L and 162 [76-251] μmol/L) compared to baseline (117 [62-216] μmol/L; P=0.003 and P<0.001 respectively), whereas serum SDMA did not change significantly at T1 but did increase by T2 (11 [8-29] μg/dL and 13 [9-24] μg/dL respectively) compared to baseline (12 [7-21] μg/dL; P=0.548 and P=0.039 respectively). There was no significant difference in baseline serum SDMA between cats that were azotaemic after treatment and those that remained non-azotaemic (12 [7-21] μg/dL, n=13 vs. 13 [11-19] μg/dL, n=6; P=0.42).

Serum SDMA concentrations are not helpful in predicting post-treatment azotaemia in initially non-azotaemic hyperthyroid cats treated with anti-thyroid medications, and might be influenced by factors other than glomerular filtration rate in hyperthyroidism.