Abstract
Objectives: To describe the effect of low-dose (111MBq) radioiodine therapy (RAI) on thyroid and renal function in hyperthyroid cats over a 12 month follow-up period.
Materials and Methods: Client-owned hyperthyroid cats underwent treatment with low-dose RAI and were followed for 12 months post-RAI treatment. Immediately prior to RAI treatment, and subsequently at one, six and 12 months post-RAI treatment, thyroid function was evaluated using total thyroxine (TT4) and thyroid stimulating hormone (TSH) and renal function was evaluated using serum creatinine concentration and glomerular filtration rate (GFR).
Results: Fifteen of the 24 (63%) cats achieved euthyroidism following low-dose RAI treatment. The incidence of development of overt hypothyroidism was 25% (6/24 cats). Of the cats developing overt hypothyroidism, 3/6 (50%) had decreased renal function, with decreased GFR preceding development of azotaemia in 2 out of 3 of these cats. Transient overt or subclinical hypothyroidism prior to restoration of euthyroidism was not observed in any cats.
Clinical Significance: Low-dose RAI is effective for most cats with hyperthyroidism, however, overt hypothyroidism may develop in some. Concurrent early decline in renal function may only be detected by measuring GFR rather than serum creatinine in some patients. Monitoring of patients post-RAI treatment should include TT4 and TSH with consideration of GFR measurement in non-azotaemic cats.
Materials and Methods: Client-owned hyperthyroid cats underwent treatment with low-dose RAI and were followed for 12 months post-RAI treatment. Immediately prior to RAI treatment, and subsequently at one, six and 12 months post-RAI treatment, thyroid function was evaluated using total thyroxine (TT4) and thyroid stimulating hormone (TSH) and renal function was evaluated using serum creatinine concentration and glomerular filtration rate (GFR).
Results: Fifteen of the 24 (63%) cats achieved euthyroidism following low-dose RAI treatment. The incidence of development of overt hypothyroidism was 25% (6/24 cats). Of the cats developing overt hypothyroidism, 3/6 (50%) had decreased renal function, with decreased GFR preceding development of azotaemia in 2 out of 3 of these cats. Transient overt or subclinical hypothyroidism prior to restoration of euthyroidism was not observed in any cats.
Clinical Significance: Low-dose RAI is effective for most cats with hyperthyroidism, however, overt hypothyroidism may develop in some. Concurrent early decline in renal function may only be detected by measuring GFR rather than serum creatinine in some patients. Monitoring of patients post-RAI treatment should include TT4 and TSH with consideration of GFR measurement in non-azotaemic cats.
| Original language | English |
|---|---|
| Pages (from-to) | 523-528 |
| Number of pages | 6 |
| Journal | Journal of Small Animal Practice |
| Volume | 60 |
| Issue number | 9 |
| Early online date | 22 Jul 2019 |
| DOIs | |
| Publication status | Published - 5 Sept 2019 |