Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system

Background: Hyperthyroidism is the most frequent endocrinopathy in older cats. To date, there is no consensus on how to best calculate the dose of radioiodine to administer to hyperthyroid cats. Aim: The goals of this study were to compare thyroid function, renal function and survival time between...

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Main Authors: Joana Matos, Bérénice Lutz, Lisa-Maria Grandt, Felix Meneses, Daniela Schweizer-Gorgas, Thierry Francey, Miguel Campos
Format: Article
Language:English
Published: Tripoli University 2022-04-01
Series:Open Veterinary Journal
Subjects:
Online Access:https://www.openveterinaryjournal.com/OVJ-2021-11-219%20J.%20Matos%20et%20al.pdf
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author Joana Matos
Bérénice Lutz
Lisa-Maria Grandt
Felix Meneses
Daniela Schweizer-Gorgas
Thierry Francey
Miguel Campos
author_facet Joana Matos
Bérénice Lutz
Lisa-Maria Grandt
Felix Meneses
Daniela Schweizer-Gorgas
Thierry Francey
Miguel Campos
author_sort Joana Matos
collection DOAJ
description Background: Hyperthyroidism is the most frequent endocrinopathy in older cats. To date, there is no consensus on how to best calculate the dose of radioiodine to administer to hyperthyroid cats. Aim: The goals of this study were to compare thyroid function, renal function and survival time between hyperthyroid cats receiving a fixed dose of radioiodine and those receiving an individualized dose calculated using a clinical scoring system. Methods: Medical records of 110 cats treated with radioiodine therapy at the University of Bern between 2010 and 2020 were reviewed. Thyroid function, renal function and survival of cats treated with a fixed dose of radioiodine (2010-2015; n= 50) were compared to those of cats treated with an individualized dose (2015-2020; n= 60) at different timepoints after therapy. Results: Treatment with a fixed dose of radioiodine (mean 168 ± 26 MBq) was associated with 69% of euthyroidism, 19% persistent hyperthyroidism and 12% hypothyroidism, whereas treatment with an individualized dose (mean 120 ± 30 MBq) led to 54% euthyroidism, 23% hyperthyroidism and 23% hypothyroidism (P=0.73). More than twelve months after treatment, the incidence of azotaemia was comparable between cats treated with a fixed dose (37%) and those treated with an individualized dose (31%) (P= 0.77). No factors were found to be predictive of treatment failure (hypothyroidism or hyperthyroidism) after therapy. Median survival time after radioiodine therapy was 44 months. In a multivariate analysis, persistent hyperthyroidism was the only variable independently associated with a shorter survival time (HR= 6.24, P= 0.002). Conclusion: The method of calculating the dose of radioiodine (fixed vs individualized) to treat feline hyperthyroidism does not appear to be decisive for post-treatment thyroid function, renal function or survival.
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spelling doaj.art-0432a51d36f8432abe0bf508e213072c2022-12-22T02:57:43ZengTripoli UniversityOpen Veterinary Journal2226-44852218-60502022-04-0112223124110.5455/OVJ.2022.v12.i2.11Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring systemJoana Matos0Bérénice Lutz1https://orcid.org/0000-0002-8640-3710Lisa-Maria Grandt2Felix Meneses3Daniela Schweizer-Gorgas4https://orcid.org/0000-0003-4600-6523Thierry Francey5https://orcid.org/0000-0002-6693-5365Miguel Campos6Small Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Länggassstrasse 128, 3012 Bern, SwitzerlandSmall Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Länggassstrasse 128, 3012 Bern, SwitzerlandSmall Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Länggassstrasse 128, 3012 Bern, SwitzerlandClinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Länggassstrasse 128, 3012 Bern, SwitzerlandClinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Länggassstrasse 128, 3012 Bern, SwitzerlandSmall Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Länggassstrasse 128, 3012 Bern, SwitzerlandSmall Animal Internal Medicine Division, Department of Clinical Veterinary Medicine, Vetsuisse Faculty University of Bern, Länggassstrasse 128, 3012 Bern, SwitzerlandBackground: Hyperthyroidism is the most frequent endocrinopathy in older cats. To date, there is no consensus on how to best calculate the dose of radioiodine to administer to hyperthyroid cats. Aim: The goals of this study were to compare thyroid function, renal function and survival time between hyperthyroid cats receiving a fixed dose of radioiodine and those receiving an individualized dose calculated using a clinical scoring system. Methods: Medical records of 110 cats treated with radioiodine therapy at the University of Bern between 2010 and 2020 were reviewed. Thyroid function, renal function and survival of cats treated with a fixed dose of radioiodine (2010-2015; n= 50) were compared to those of cats treated with an individualized dose (2015-2020; n= 60) at different timepoints after therapy. Results: Treatment with a fixed dose of radioiodine (mean 168 ± 26 MBq) was associated with 69% of euthyroidism, 19% persistent hyperthyroidism and 12% hypothyroidism, whereas treatment with an individualized dose (mean 120 ± 30 MBq) led to 54% euthyroidism, 23% hyperthyroidism and 23% hypothyroidism (P=0.73). More than twelve months after treatment, the incidence of azotaemia was comparable between cats treated with a fixed dose (37%) and those treated with an individualized dose (31%) (P= 0.77). No factors were found to be predictive of treatment failure (hypothyroidism or hyperthyroidism) after therapy. Median survival time after radioiodine therapy was 44 months. In a multivariate analysis, persistent hyperthyroidism was the only variable independently associated with a shorter survival time (HR= 6.24, P= 0.002). Conclusion: The method of calculating the dose of radioiodine (fixed vs individualized) to treat feline hyperthyroidism does not appear to be decisive for post-treatment thyroid function, renal function or survival.https://www.openveterinaryjournal.com/OVJ-2021-11-219%20J.%20Matos%20et%20al.pdfcatdosehyperthyroidismradioiodine
spellingShingle Joana Matos
Bérénice Lutz
Lisa-Maria Grandt
Felix Meneses
Daniela Schweizer-Gorgas
Thierry Francey
Miguel Campos
Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system
Open Veterinary Journal
cat
dose
hyperthyroidism
radioiodine
title Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system
title_full Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system
title_fullStr Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system
title_full_unstemmed Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system
title_short Outcome of radioiodine therapy for feline hyperthyroidism: Fixed dose versus individualized dose based on a clinical scoring system
title_sort outcome of radioiodine therapy for feline hyperthyroidism fixed dose versus individualized dose based on a clinical scoring system
topic cat
dose
hyperthyroidism
radioiodine
url https://www.openveterinaryjournal.com/OVJ-2021-11-219%20J.%20Matos%20et%20al.pdf
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