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Title: Radioactive iodine therapy in cats with hyperthyroidism

Eleven cats with hyperthyroidism were treated with radioactive iodine (/sup 131/I). Previous unsuccessful treatments for hyperthyroidism included hemithyroidectomy (2 cats) and an antithyroid drug (7 cats). Two cats had no prior treatment. Thyroid scans, using technetium 99m, showed enlargement and increased radionuclide accumulation in 1 thyroid lobe in 5 cats and in both lobes in 6 cats. Serum thyroxine concentrations were high and ranged from 4.7 to 18 micrograms/dl. Radioactive iodine tracer studies were used to determine peak radioactive iodine uptake (RAIU) and effective and biological half-lives. Activity of /sup 131/I administered was calculated from peak RAIU, effective half-life, and estimated thyroid gland weight. Activity of /sup 131/I administered ranged from 1.0 to 5.9 mCi. The treatment goal was to deliver 20,000 rad to hyperactive thyroid tissue. However, retrospective calculations based on peak RAIU and effective half-life obtained during the treatment period showed that radiation doses actually ranged from 7,100 to 64,900 rad. Complete ablation of the hyperfunctioning thyroid tissue and a return to euthyroidism were seen in 7 cats. Partial responses were seen in 2 cats, and 2 cats became hypothyroid. It was concluded that /sup 131/I ablation of thyroid tumors was a reasonable alternative in the treatment ofmore » hyperthyroidism in cats. The optimal method of dosimetry remains to be determined.« less
Authors:
; ; ;
Publication Date:
OSTI Identifier:
6830928
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Am. Vet. Med. Assoc.; (United States); Journal Volume: 184:5
Research Org:
Department of Radiological Sciences, School of Veterinary Medicine, University of California, Davis
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; 62 RADIOLOGY AND NUCLEAR MEDICINE; HYPERTHYROIDISM; RADIOTHERAPY; CATS; DOSE-RESPONSE RELATIONSHIPS; IODINE 131; ANIMALS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; DAYS LIVING RADIOISOTOPES; DISEASES; ENDOCRINE DISEASES; INTERMEDIATE MASS NUCLEI; IODINE ISOTOPES; ISOTOPES; MAMMALS; MEDICINE; NUCLEAR MEDICINE; NUCLEI; ODD-EVEN NUCLEI; RADIOISOTOPES; RADIOLOGY; THERAPY; VERTEBRATES 560162* -- Radionuclide Effects, Kinetics, & Toxicology-- Animals, Plants, Microorganisms, & Cells; 550604 -- Medicine-- Unsealed Radionuclides in Therapy-- (1980-)