Peer-reviewed veterinary case report
Radioactive iodine dose and survival in cats with hyperthyroidism
By Chow, Joyce Ly & White, Joanna·Published in Journal of feline medicine and surgery·2022·Small Animal Specialist Hospital, Australia·View original on PubMed →
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Original publication title: Radioactive iodine dose and survival in cats with hyperthyroidism (2015-2020).
- Species:
- cat
Plain-English summary
A group of hyperthyroid cats, treated with radioactive iodine, showed varying survival rates based on their kidney function and age. The study involved 198 cats, with a median survival time of about 3 years. It was found that higher levels of creatinine in the blood after treatment and older age were linked to a greater risk of death. While the dose of radioactive iodine didn't directly affect survival, managing thyroid hormone levels after treatment could help improve outcomes.
People also search for: cat hyperthyroidism treatment · radioactive iodine for cats · cat kidney function after treatment
Abstract
OBJECTIVES: Radioactive iodine (I) is the preferred treatment for feline hyperthyroidism but neither the optimalI dose nor consistent predictors of post-treatment azotaemia have been determined. The aims of the study were to evaluate the relationships between: (1)I dose and survival; and (2) pretreatment and post-treatment serum creatinine concentration. METHODS: Medical records of hyperthyroid cats treated withI at a single referral hospital were reviewed. Information regarding signalment, body weight, pretreatment and post-treatment serum total thyroxine concentration (TT4), serum creatinine concentration,I dose and survival were determined. Multivariable Cox proportional hazards analysis was used to identify variables associated with survival. Multivariable linear regression analysis was used to identify variables associated with post-treatment serum creatinine concentration. RESULTS: One hundred and ninety-eight (79 male, 119 female) cats were treated for hyperthyroidism withI (median dose 138 MBq; interquartile range 92-168). Median survival time was 1153 days (range 16-1871). Post-treatment serum creatinine (<0.001) and age ( = 0.049) were significantly associated with survival. Every 10 µmol/l increase in post-treatment serum creatinine concentration and every year increase in age was associated with a 1.07-fold (confidence interval [CI] 1.04-1.11) and 1.17-fold (CI 1.00-1.37) increase in the daily hazard of death, respectively. Pretreatment serum creatinine concentration was directly, and post-treatment serum TT4 concentration was inversely, associated with post-treatment serum creatinine concentration. Every 1 μmol/l increase in pretreatment serum creatinine concentration was associated with an increase in post-treatment serum creatinine concentration of 0.7 μmol/l (SE 0.17;<0.001). Conversely, every 1 nmol/l decrease in post-treatment serum TT4 concentration was associated with a 1.2 μmol/l (SE 0.61;<0.001) increase in post-treatment serum creatinine concentration. CONCLUSIONS AND RELEVANCE: Post-treatment serum TT4 concentration was associated with post-treatment azotaemia, which was associated with survival. AlthoughI dose was not directly associated with survival, dosing strategies that minimise post-treatment hypothyroidism and azotaemia could improve patient survival.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/34730466/