Effect of the Stage of Chronic Kidney Disease on Serum Total Thyroxine in Cats

Vieira A.B., Castro M., Salomao M., et al.

Conference Proceedings, (2012). American College of Veterinary Internal Medicine, New Orleans: p.755


Non-thyroidal illnesses, such as chronic kidney disease, are one of the factors that can affect total thyroxine and hinder the diagnosis of hyperthyroidism in cats. Cats with chronic kidney disease are currently staged according to the degree of azotemia based on the IRIS (International Renal Interest Society) guide- lines. The purpose of the present study was to determine the influence of chronic kidney disease stage on serum total thyroxine (TT4) in cats.

Total thyroxine was measured by chemiluminescent immunometric assay in the serum of 32 healthy cats and 33 cats with various degrees of chronic kidney disease. Nineteen cats were classified as IRIS stage 2, nine cats as IRIS stage 3 and four cats as IRIS stage 4.

Cats with chronic kidney disease had significantly lower (p<0.0001) mean serum TT4 concentrations than clinically healthy cats. Mean serum TT4 concentration decreased 34.73% in the IRIS stage 2 group, 41.67% in the IRIS stage 3 group and 55.58% in the IRIS stage 4 group when compared to the control group. Even though mean TT4 concentrations decreased with the increase of azotemia in the CKD groups, values were only signifi- cantly different when compared to cats in the control group.

Results obtained in the present study suggest that any stage of chronic kidney disease can lead to the suppression of total thyroxine concentration in cats.