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Survival and the development of azotemia after treatment of hyperthyroid cats
T L Williams1, K J Peak, D Brodbelt
1Department of Veterinary Clinical Sciences, Royal Veterinary College, North Mymms, Hatfield, UK. twilliams@rvc.ac.uk
Insights
Hyperthyroidism in cats can mask chronic kidney disease (CKD). While proteinuria doesn't worsen CKD, certain clinical markers at diagnosis can predict azotemia and survival in hyperthyroid cats.
Area of Science:
- Veterinary Medicine
- Nephrology
- Endocrinology
Background:
- Hyperthyroidism complicates chronic kidney disease (CKD) diagnosis by increasing glomerular filtration rate.
- No reliable method currently exists to identify cats that will develop azotemia post-hyperthyroidism treatment.
- Hyperthyroidism is linked to proteinuria, which correlates with decreased survival and CKD progression.
Purpose of the Study:
- To determine if proteinuria and other clinical parameters at hyperthyroidism diagnosis predict azotemia development and survival time.
- To identify predictive factors for azotemia and mortality in hyperthyroid cats.
Main Methods:
- Retrospective cohort study of 300 client-owned hyperthyroid cats.
- Analysis of clinical parameters at diagnosis, including plasma urea, creatinine, globulin, urine protein:creatinine ratio, and hypertension.
- Multivariable logistic and Cox regression analyses to identify predictors of azotemia and survival.
Main Results:
- 15.3% of cats developed azotemia within 240 days of diagnosis.
- Elevated plasma urea and creatinine correlated with azotemia development.
- Age, urine protein:creatinine ratio, and hypertension correlated with decreased survival.
- Urine specific gravity and packed cell volume (PCV) correlated with increased survival.
Conclusions:
- Proteinuria in hyperthyroid cats does not appear to mediate CKD progression.
- Proteinuria is associated with all-cause mortality in hyperthyroid cats.
- Clinical parameters at diagnosis can predict azotemia and survival, aiding in risk assessment.
Background:
Hyperthyroidism complicates the diagnosis of chronic kidney disease (CKD) as it increases glomerular filtration rate. No practical and reliable means for identifying those cats that will develop azotemia after treatment for hyperthyroidism has been identified. Hyperthyroidism is associated with proteinuria. Proteinuria has been correlated with decreased survival of cats with CKD and with progression of CKD.
Hypothesis:
Proteinuria and other clinical parameters measured at diagnosis of hyperthyroidism will be associated with the development of azotemia and survival time.
Animals:
Three hundred client owned hyperthyroid cats treated in first opinion practice.
Methods:
Retrospective, cohort study relating clinical parameters in hyperthyroid cats at diagnosis to the development of azotemia within 240 days of diagnosis and survival time (all cause mortality). Multivariable logistic regression analysis was used to identify factors that were predictive of the development of azotemia. Multivariable Cox regression analysis was used to identify factors associated with survival.
Results:
Three hundred cats were eligible for survival analysis and 216 cats for analysis of factors associated with the development of azotemia. The median survival time was 417 days, and 15.3% (41/268) cats developed azotemia within 240 days of diagnosis of hyperthyroidism. Plasma concentrations of urea and creatinine were positively correlated with the development of azotemia. Plasma globulin concentration was negatively correlated with the development of azotemia. Age, urine protein:creatinine ratio, and the presence of hypertension were significantly correlated with decreased survival time. Urine specific gravity and PCV were significantly correlated with increased survival time.
Conclusions And Clinical Importance:
The proteinuria associated with hyperthyroidism is not a mediator of progression of CKD; however, it does correlate with all cause mortality.
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