Peer-reviewed veterinary case report
Radioiodine treatment success for hyperthyroid cats in Spain
By Xifra, Pilar et al.·Published in Journal of Feline Medicine and Surgery·2022·IODOCAT, Madrid, Spain, Spain·View original on Crossref →
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Original publication title: Radioiodine treatment of hyperthyroidism in cats: results of 165 cats treated by an individualised dosing algorithm in Spain
- Species:
- cat
Plain-English summary
A group of 165 hyperthyroid cats, including various breeds, were treated with a new personalized radioiodine (131 I) dosing method to manage their condition. This approach aimed to reduce the risk of side effects like hypothyroidism and kidney problems while still effectively treating the hyperthyroidism. After treatment, about 75% of the cats became normal in thyroid function, while a small number developed mild or severe hypothyroidism. The study found that older cats and those with certain thyroid uptake patterns were more likely to experience complications. Overall, the new dosing method showed promising results in treating feline hyperthyroidism with fewer adverse effects.
People also search for: cat hyperthyroidism treatment · radioiodine therapy for cats · symptoms of cat thyroid problems
Abstract
Objectives Although radioiodine ( 131 I) is the treatment of choice for feline hyperthyroidism, 131 I-dosing protocols commonly induce iatrogenic hypothyroidism and expose azotaemia. A recently reported patient-specific 131 I dosing algorithm minimised the risk of 131 I-induced hypothyroidism and azotaemia, while maintaining high cure rates. The aim of the study was to report results of 131 I treatment in a European population of hyperthyroid cats using this patient-specific dosing algorithm. Methods This prospective case series (before-and-after study) evaluated 165 hyperthyroid cats referred for 131 I treatment. All cats had serum concentrations of thyroxine (T4), triiodothyronine (T3) and thyroid-stimulating hormone (TSH) measured (off methimazole ⩾1 week). Thyroid volume and percentage uptake of 99m Tc-pertechnetate (TcTU) were determined using thyroid scintigraphy. An initial 131 I dose was calculated by averaging dose scores for T4/T3 concentrations, thyroid volume and TcTU; 70% of that composite dose was then administered. Twenty-four hours later, percentage 131 I uptake was measured, and additional 131 I administered as needed to deliver an adequate radiation dose to the thyroid tumour(s). Serum concentrations of T4, TSH and creatinine were determined 6–12 months later. Results Median calculated 131 I dose was 2.15 mCi (range 1.2–7.5), with only 51 (30.9%) receiving ⩾2.5 mCi. Of 165 cats, 124 (75.2%) became euthyroid, seven (4.2%) became overtly hypothyroid, 27 (16.4%) became subclinically hypothyroid and seven (4.2%) remained hyperthyroid. A higher proportion of overtly (85.7%) and subclinically (26.9%) hypothyroid cats developed azotaemia than euthyroid cats (13.6%; P = 0.0002). Hypothyroid cats were older ( P = 0.016) and more likely to have detectable TSH concentrations ( P = 0.025) and symmetrical bilateral distribution of 99m Tc-pertechnetate uptake ( P = 0.0002), whereas persistently hyperthyroid cats had higher severity scores ( P = 0.012). Conclusions and relevance Our results confirm that 131 I dosing with this new algorithm results in high cure rates, with a lowered prevalence of 131 I-induced overt hypothyroidism and azotaemia. Age, serum TSH concentrations, bilateral, symmetrical uptake and severity score help predict outcome.
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Search related cases →Original publication on Crossref: https://doi.org/10.1177/1098612x221104743