Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism
Abstract Background Hyperthyroid cats that are azotemic and hypothyroid after surgical or medical treatment have poor outcomes, and supplementation with levothyroxine (LT4) improves survival. However, the effect of LT4 supplementation on survival of nonazotemic, hypothyroid radioiodine (RI)‐treated...
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Wiley
2025-01-01
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| Series: | Journal of Veterinary Internal Medicine |
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| Online Access: | https://doi.org/10.1111/jvim.17295 |
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| author | Sarah E. Cox Jennifer Wakeling Teresa Hall Tim L. Williams |
| author_facet | Sarah E. Cox Jennifer Wakeling Teresa Hall Tim L. Williams |
| author_sort | Sarah E. Cox |
| collection | DOAJ |
| description | Abstract Background Hyperthyroid cats that are azotemic and hypothyroid after surgical or medical treatment have poor outcomes, and supplementation with levothyroxine (LT4) improves survival. However, the effect of LT4 supplementation on survival of nonazotemic, hypothyroid radioiodine (RI)‐treated hyperthyroid cats is unknown. Hypothesis Radioiodine treated hyperthyroid cats with iatrogenic hypothyroidism or azotemia have shorter survival times than euthyroid, nonazotemic cats and supplementation of LT4 improves survival times of hypothyroid cats. Animals One hundred seventeen RI treated hyperthyroid cats. Methods Prospective cohort study. Radioiodine treated cats were screened for azotemia and iatrogenic hypothyroidism using TSH stimulation test; LT4 supplementation was offered to all hypothyroid cats with decision to treat based on owner preference. The log rank test was used to compare survival times between groups, and the Mann‐Whitney U test was used to compare age and renal variables. Data are presented as median [range]. Results Euthyroid azotemic cats (934 [759‐2035] days) and nonsupplemented hypothyroid cats (azotemic and nonazotemic combined, 1232 [238‐2363] days) had shorter survival times than euthyroid nonazotemic cats (1616 [663‐3369] days, P = .003 and P = .002, respectively). Levothyroxine supplemented hypothyroid nonazotemic cats had longer survival times than nonsupplemented hypothyroid nonazotemic cats (1037 [300‐2401] days vs 768 [34‐1014] days; P = .027). Levothyroxine supplementation was not associated with prolonged survival times in hypothyroid azotemic cats vs nonsupplemented hypothyroid azotemic cats (771 [718‐1558] days vs 152 [82‐1852] days, respectively, P = .991). Conclusions and Clinical Importance Levothyroxine supplementation in nonazotemic cats with iatrogenic hypothyroidism (diagnosed based on TSH stimulation test results) improved survival times, although randomized controlled trials are needed. |
| format | Article |
| id | doaj-art-29b2be3bbd85407d9f1ed776ddbd2854 |
| institution | Kabale University |
| issn | 0891-6640 1939-1676 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Wiley |
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| series | Journal of Veterinary Internal Medicine |
| spelling | doaj-art-29b2be3bbd85407d9f1ed776ddbd28542025-01-27T15:22:41ZengWileyJournal of Veterinary Internal Medicine0891-66401939-16762025-01-01391n/an/a10.1111/jvim.17295Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidismSarah E. Cox0Jennifer Wakeling1Teresa Hall2Tim L. Williams3Department of Veterinary Medicine University of Cambridge Cambridge UKDouglas College Coquitlam British Columbia CanadaNorth West Nuclear Medicine Vancouver British Columbia CanadaDepartment of Veterinary Medicine University of Cambridge Cambridge UKAbstract Background Hyperthyroid cats that are azotemic and hypothyroid after surgical or medical treatment have poor outcomes, and supplementation with levothyroxine (LT4) improves survival. However, the effect of LT4 supplementation on survival of nonazotemic, hypothyroid radioiodine (RI)‐treated hyperthyroid cats is unknown. Hypothesis Radioiodine treated hyperthyroid cats with iatrogenic hypothyroidism or azotemia have shorter survival times than euthyroid, nonazotemic cats and supplementation of LT4 improves survival times of hypothyroid cats. Animals One hundred seventeen RI treated hyperthyroid cats. Methods Prospective cohort study. Radioiodine treated cats were screened for azotemia and iatrogenic hypothyroidism using TSH stimulation test; LT4 supplementation was offered to all hypothyroid cats with decision to treat based on owner preference. The log rank test was used to compare survival times between groups, and the Mann‐Whitney U test was used to compare age and renal variables. Data are presented as median [range]. Results Euthyroid azotemic cats (934 [759‐2035] days) and nonsupplemented hypothyroid cats (azotemic and nonazotemic combined, 1232 [238‐2363] days) had shorter survival times than euthyroid nonazotemic cats (1616 [663‐3369] days, P = .003 and P = .002, respectively). Levothyroxine supplemented hypothyroid nonazotemic cats had longer survival times than nonsupplemented hypothyroid nonazotemic cats (1037 [300‐2401] days vs 768 [34‐1014] days; P = .027). Levothyroxine supplementation was not associated with prolonged survival times in hypothyroid azotemic cats vs nonsupplemented hypothyroid azotemic cats (771 [718‐1558] days vs 152 [82‐1852] days, respectively, P = .991). Conclusions and Clinical Importance Levothyroxine supplementation in nonazotemic cats with iatrogenic hypothyroidism (diagnosed based on TSH stimulation test results) improved survival times, although randomized controlled trials are needed.https://doi.org/10.1111/jvim.17295azotemiablood pressurechronic kidney diseasefeline |
| spellingShingle | Sarah E. Cox Jennifer Wakeling Teresa Hall Tim L. Williams Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism Journal of Veterinary Internal Medicine azotemia blood pressure chronic kidney disease feline |
| title | Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism |
| title_full | Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism |
| title_fullStr | Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism |
| title_full_unstemmed | Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism |
| title_short | Survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment, and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism |
| title_sort | survival of radioiodine treated hyperthyroid cats that are euthyroid and hypothyroid after treatment and effect of levothyroxine supplementation on survival time of cats with iatrogenic hypothyroidism |
| topic | azotemia blood pressure chronic kidney disease feline |
| url | https://doi.org/10.1111/jvim.17295 |
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