Commercially available recombinant human thyroid-stimulating hormone effectively stimulates total and free thyroxine concentrations in Quaker parrots (Myopsitta monachus), including at low doses and after freezing.

Abstract

Objective: To develop a protocol for thyroid-stimulating hormone (TSH) stimulation testing in psittacine birds using thyrotropin alfa (Thyrogen; Sanofi).

Methods: Quaker parrots (Myopsitta monachus) were randomized to receive an IM injection of freshly reconstituted high-dose recombinant human TSH (rhTSH; 8 parrots), frozen high-dose rhTSH (8), frozen low-dose rhTSH (8), or saline (8). Total T4 (TT4), free T4 (FT4), T3, and TSH were measured pre- and 4 hours postinjection.

Results: TSH stimulation testing was completed in 31 of the 32 birds. Thyroid-stimulating hormone measurement confirmed proper administration of rhTSH. Median TT4 at baseline in the population was 0.14 μg/dL (range, 0.03 to 0.33 µg/dL). Poststimulation, the median TT4 in rhTSH-treated parrots was 1.31 µg/dL (0.29 to 1.98 µg/dL) versus 0.09 µg/dL (0.04 to 0.14 µg/dL) in control parrots. All parrots administered rhTSH had an increase in TT4 (minimum, 3.5-fold) and FT4 (minimum, 2.2-fold) from baseline but not in T3. Parrots administered saline had no increase in TT4, FT4, or T3. Postinjection concentrations of TT4, but not of FT4 or T3, showed no overlap between controls and rhTSH-treated parrots.

Conclusions: TSH stimulation testing performed with fresh and frozen rhTSH for 3 months is feasible and safe and results in a significant increase in TT4 in Quaker parrots. Total T4 should be the preferred outcome measure for TSH stimulation testing in parrots.

Clinical relevance: Thyrogen can be used at doses as low as 0.01 mL (73 µg/kg) for TSH stimulation tests in Quaker parrots and can be frozen in aliquots to perform more tests per vial.