Paired pre-and post-treatment serum biochemical parameters and thyroxine concentrations in a cohort of ninety seven radioiodine-treated hyperthyroid cats

Serum hepatic and renal parameters from a 97 hyperthyroid cat cohort, sampled within 2 weeks before and 8-11 weeks after oral radioiodine treatment, were retrospectively reviewed for: 1.relationships between pre-treatment total serum thyroxine concentration (T4) and the biochemical values; 2. degree of value change; and 3. influence of pre-treatment methimazole exposure or concurrent cardiac management drugs on the values. Spearmen's ranked correlation, chi-square, Kruskal-Wallis, and Mann-Whitney techniques were used. Weak statistically significant correlations between the pre-treatment T4 and the degree of ALP, ALT, and AST abnormality and between the degree of post-treatment T4, ALP, and ALT reduction were found. The degree of T4 change was greater in methimazole-exposed and cardiac drug-treated cats. The BUN and creatinine significantly increased post-treatment; about half of the cats became azotemic (varying degrees). No significant relationship was found between the pre-treatment T4 or the T4 reduction and the increase in BUN and creatinine values.