Use of recombinant human thyroid-stimulating hormone for thyrotropin-stimulation testing of euthyroid cats.
OBJECTIVE
To evaluate response of euthyroid cats to administration of recombinant human thyroid-stimulating hormone (rhTSH).


METHODS
7 healthy cats.


METHODS
Each cat received each of 5 doses of rhTSH (0, 0.025, 0.050, 0.100, and 0.200 mg), IV, at 1-week intervals. Serum concentration of total thyroxine (TT4) and free thyroxine (fT4) was measured immediately before each injection (time 0) and 2, 4, 6, and 8 hours after administration of each dose.


RESULTS
Overall TT4 response did not differ significantly among cats when administered doses were > or = 0.025 mg. Serum TT4 concentrations peaked 6 to 8 hours after administration for all doses > or = 0.025 mg. For all doses > or = 0.025 mg, mean +/- SEM TT4 concentration at 0, 6, and 8 hours was 33.9 +/- 1.7, 101.8 +/- 5.9, and 101.5 +/- 5.7 nmol/L, respectively. For all doses > or = 0.025 mg, mean fT4 concentration at 0, 6, and 8 hours was 38.7 +/- 2.9, 104.5 +/- 7.6, and 100.4 +/- 8.0 pmol/L, respectively. At 8 hours, the fT4 response to 0.025 and 0.050 mg was less than the response to 0.100 and 0.200 mg. Adverse reactions after rhTSH administration were not detected.


CONCLUSIONS
The TSH stimulation test can be performed in cats by IV administration of 0.025 to 0.200 mg of rhTSH and measurement of serum TT4 concentrations at time of injection and 6 or 8 hours later. Clinical validation of the TSH stimulation test would facilitate development of additional tests of thyroid gland function, such as a TSH assay.
Stegeman
Julie R
JR
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824-1314, USA.
Graham
Peter A
PA
Hauptman
Joe G
JG
D000818:Animals; D002371:Cat Diseases / Q000097:blood / Q000175:diagnosis*; D002415:Cats; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis* / Q000662:veterinary*; D008297:Male; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D013961:Thyroid Gland / Q000187:drug effects / Q000502:physiology; D013972:Thyrotropin / Q000008:administration & dosage* / Q000097:blood* / Q000494:pharmacology; D013974:Thyroxine / Q000097:blood; D013997:Time Factors
D011994:Recombinant Proteins; D013972:Thyrotropin; D013974:Thyroxine