The Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) is pleased to announce the validation of a new endogenous adrenocorticotropic hormone (ACTH) test for equines. Endogenous ACTH aids in the diagnosis of pituitary pars intermedia dysfunction (PPID) when interpreted in conjunction with clinical signs. ACTH is an unstable hormone and this new assay provides increased accuracy and precision without an increase in price.
PPID is a neurodegenerative disease of the dopaminergic periventricular neurons of the hypothalamus that project and physiologically inhibit the pituitary gland. This results in an excessive production of pro-opiomelanocortin (POMC) and its related peptides, including ACTH. The cause of this degeneration is multifactorial and not yet fully understood. Clinical signs of PPID include hirsutism, polyuria/polydipsia, laminitis, excessive sweating, and lethargy.
Measurement of endogenous ACTH is recommended in aging horses displaying clinical signs of PPID. In horses with moderate to severe clinical signs, a single endogenous ACTH measurement may be diagnostic. In horses with mild clinical signs or equivocal single endogenous ACTH results, TRH stimulation testing may be warranted (endogenous ACTH measured before and after TRH administration); the latter cannot be performed between mid-July and mid-November. Additionally, endogenous ACTH should be measured at least every six months in horses undergoing treatment for PPID.
The ideal specimen for ACTH is EDTA plasma that is harvested within 60 minutes of collection and frozen in plastic tubes until the assay is performed. Detailed collection and submission guidelines are available on our website.
The new endogenous ACTH assay at TVMDL is a radioimmunoassay (RIA) that has been validated through a robust quality assurance study. With this new assay, TVMDL can provide more accurate and precise endogenous ACTH results to veterinarians and animal owners. The turnaround time for endogenous ACTH will be decreased from 14 days to 7 days. In the future, shorter turnaround times may also be available. All endogenous ACTH results are accompanied by interpretive guidelines, including thresholds for seasonal variation. Additionally, endocrinologists, clinical pathologists, and diagnosticians are always available for consultations.
Test: ACTH – Endogenous (RIA)
Turnaround: This test is performed at the College Station laboratory on Mondays with results in 7 business days.
To learn more about TVMDL’s test offerings, visit tvmdl.tamu.edu or call 1.888.646.5623.