title: Evaluation of a thyrotropin-releasing hormone solution stored at room temperature for pituitary pars intermedia dysfunction testing in horses.
abstract: OBJECTIVE
  To determine whether plasma ACTH concentrations vary following administration of a thyrotropin-releasing hormone (TRH) solution prepared for research purposes and stored at -20°C (rTRH) or prepared by a compounding pharmacy and stored at room temperature (approx 22°C; cTRH).
  
  
  METHODS
  34 adult horses.
  
  
  METHODS
  The study consisted of 2 experiments. In experiment 1, each horse underwent 2 TRH stimulation tests separated by 24 hours; 10 horses were administered cTRH for the first test and rTRH for the second test (group 1), 10 horses were administered rTRH for the first test and cTRH for the second test (group 2), and 10 horses were administered rTRH for both tests (group 3). Plasma ACTH concentrations were measured at 0 (baseline) and 30 minutes after TRH administration and the delta ACTH responses (change in ACTH concentration after TRH administration) were calculated. In experiment 2, the design was the same as that for experiment 1 except there were 14 days between tests, ACTH was measured at 0 and 10 minutes after TRH administration, and 11, 9, and 10 horses were assigned to groups 1, 2, and 3, respectively.
  
  
  RESULTS
  Adverse effects associated with TRH administration included transient coughing and yawning. In experiment 1, the median delta ACTH response for the second test was significantly lower than that for the first test for all groups. In experiment 2, the median delta ACTH response did not differ significantly between the first and second tests for any group, ACTH concentrations after rTRH administration were positively correlated (rs = 0.95) with those after cTRH administration, and the mean ± SD bias in post-TRH ACTH concentration between rTRH and cTRH was 2.9 ± 12.4 pg/mL.
  
  
  CONCLUSIONS
  Results indicated that the TRH stimulation test should not be repeated within 24 hours, and cTRH solution stored at room temperature could be used to effectively perform TRH stimulation testing in horses.
authors.affiliation: Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Goodale
authors.forename: Nicholas
authors.initials: N
authors.lastname: Frank
authors.forename: Pilar
authors.initials: P
authors.lastname: Hermida
authors.forename: Sarah
authors.initials: S
authors.lastname: D'Oench
mesh_terms: D061605:Administration, Intravenous / Q000662:veterinary; D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000818:Animals; D005260:Female; D006736:Horses / Q000378:metabolism*; D008297:Male; D052716:Pituitary Gland, Intermediate / Q000378:metabolism*; D013696:Temperature; D013973:Thyrotropin-Releasing Hormone / Q000097:blood*; D014730:Veterinary Medicine / Q000379:methods*
chemical_list: D013973:Thyrotropin-Releasing Hormone; D000324:Adrenocorticotropic Hormone