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ABSTRACT: Background
Radioiodine (131 I) is effective treatment for hyperthyroidism in cats, but optimal dose to restore euthyroidism without inducing hypothyroidism is unclear. Treatment-induced hypothyroidism can lead to azotemia and reduced duration of survival.Objective
To compare efficacy and short-term outcomes of low-dose 131 I versus higher, standard-dose 131 I as treatment for hyperthyroidism.Animals
A total of 189 client-owned cats undergoing 131 I treatment for mild-to-moderate hyperthyroidism (serum T4 ? 4.0 ?g/dL and <13.0 ?g/dL).Methods
Prospective, nonrandomized, cohort study comparing treatment with either low-dose (2 mCi, n = 150) or standard-dose (4 mCi, n = 39) 131 I. Serum T4 , thyroid-stimulating hormone (TSH), and creatinine concentrations were measured after 1, 3, and 6 months to determine persistent hyperthyroidism, overt hypothyroidism (low T4 , high TSH), subclinical hypothyroidism (normal T4 , high TSH), and azotemia.Results
There was no significant difference in prevalence of cats with persistent hyperthyroidism between standard- and low-dose treatment groups at 3 (0% versus 5.3%; P = .34) and 6 (0% versus 3.3%; P = .51) months. Overt (18% versus 1%; P = .0005) or subclinical (46% versus 21%; P = .004) hypothyroidism was more common in cats at 6 months after standard-dose 131 I. No difference in incidence of azotemia existed between groups, but cats treated with standard-dose 131 I had higher creatinine concentrations (P < .05) and higher percent rises in creatinine (P < .0001).Conclusions and clinical importance
Low-dose 131 I is safe and effective for cats with mild-to-moderate hyperthyroidism, as evidenced by a cure rate of >95% with reduced frequency of iatrogenic hypothyroidism and azotemia.
SUBMITTER: Lucy JM
PROVIDER: S-EPMC5354058 | biostudies-literature | 2017 Mar
REPOSITORIES: biostudies-literature
Lucy J M JM Peterson M E ME Randolph J F JF Scrivani P V PV Rishniw M M Davignon D L DL Thompson M S MS Scarlett J M JM
Journal of veterinary internal medicine 20170203 2
<h4>Background</h4>Radioiodine (<sup>131</sup> I) is effective treatment for hyperthyroidism in cats, but optimal dose to restore euthyroidism without inducing hypothyroidism is unclear. Treatment-induced hypothyroidism can lead to azotemia and reduced duration of survival.<h4>Objective</h4>To compare efficacy and short-term outcomes of low-dose <sup>131</sup> I versus higher, standard-dose <sup>131</sup> I as treatment for hyperthyroidism.<h4>Animals</h4>A total of 189 client-owned cats undergo ...[more]