Peer-reviewed veterinary case report
Thyroid to background ratio helps predict iodine treatment success
By Wallack, Seth et al.·Published in Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association·2010·VICSD, United States·View original on PubMed →
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Original publication title: Calculation and usage of the thyroid to background ratio on the pertechnetate thyroid scan.
- Species:
- cat
Plain-English summary
A group of hyperthyroid cats underwent a special thyroid scan before receiving a standard treatment dose of radioactive iodine. Out of 113 cats, 107 responded well to the treatment, while 6 did not improve. The cats that didn't respond had a higher thyroid to background ratio on their scans, suggesting they might need a higher dose of treatment to be effective. This new method of evaluating the scans could help veterinarians identify which cats are at risk of treatment failure and adjust their care accordingly.
People also search for: cat hyperthyroidism treatment · radioactive iodine for cats · why is my cat still hyperthyroid after treatment
Abstract
Feline hyperthyroidism is a common endocrine disorder. A single dose of 148MBq (4mCi) 131I is 95-98% effective for the treatment of hyperthyroidism in cats; however, the cause for treatment failures has not been determined. In a series of 113 hyperthyroid cats having pertechnetate thyroid scintigraphy before treatment using a standard 148MBq (4mCi) 131I dose, the thyroid to salivary gland (T:S) ratio and the thyroid to background (T:B) ratio were calculated. Results in 107 (95%) cats successfully treated were compared with results in six (5%) cats that remained hyperthyroid after treatment. T:B ratio was significantly higher for cats that had treatment failure (median 13.0, range 3.6-73.0) than for cats successfully treated (median 4.4, range 1.2-69.0) (P = 0.02), whereas there was no significant difference in their T:S ratios (P = 0.2). The T:B ratio is a new approach to evaluating the thyroid pertechnetate scan with the intent of identifying which hyperthyroid cats may fail treatment using a standard 148 MBq (4 mCi) 131 dose and which, therefore, require a higher dose.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/20973392/