Open AccessRecombinant Human Thyrotropin Administration Enhances Thyroid Uptake of Radioactive Iodine in Hyperthyroid Cats
Author(s) -
Van Hoek I.,
Daminet S.,
Vandermeulen E.,
Dobbeleir A.,
Duchateau L.,
Peremans K.
Publication year - 2008
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/j.1939-1676.2008.0191.x
Subject(s) - medicine , cats , radioactive iodine , iodine , endocrinology , urine , thyroid , urology , materials science , metallurgy
Background: Hyperthyroidism is the most diagnosed endocrine disorder in cats and radioiodine ( 131 I) is the treatment of choice. The dose emission rate and radioactivity in urine, saliva, and on hair and paws are determined by the dose of administered 131 I. A dose reduction of therapeutic 131 I could possibly be achieved after recombinant human thyrotropin (rhTSH) administration as in humans with nodular goiter. Hypothesis: rhTSH will increase radioiodine uptake in hyperthyroid cats. Animals: Five hyperthyroid cats. Methods: Twenty‐five micrograms rhTSH (day 1) or 2 mL 0.9% sodium chloride (NaCl) (day 9) was injected IV. One hour later, 11.4 ± 4.1 (mean ± SD) MBq 123 I was injected IV. Radioactive iodine uptake (RAIU) was measured 6, 12, and 24 hours after rhTSH (RAIU‐rhTSH) or NaCl (RAIU‐blanco) injection. Blood samples for measurement of TT4 were taken before injection of rhTSH or NaCl (TT4 0 ) and at the time of imaging. Results: Percentages of RAIU‐rhTSH (and RAIU‐blanco) at 6, 12, and 24 hours after administration of rhTSH were 34 ± 18 (31 ± 21), 46 ± 20 (38 ± 18), and 47 ± 15 (36 ± 14). There was a statistically significant effect of rhTSH administration on RAIU ( P = .043) but not on serum TT4 concentration. Baseline serum TT4 0 concentration influenced RAIU‐rhTSH significantly at 6 hours ( P = .037). Conclusion and Clinical Importance: The increased RAIU observed after rhTSH administration in hyperthyroid cats could lead to a lower therapeutic dose of 131 I after rhTSH administration in hyperthyroid cats and decreased risk of environmental and owner contamination during and after hospitalization.