Hypothalamic-pituitary-adrenal axis dysfunction in hospitalized neonatal foals.
BACKGROUND
Transient hypothalamic-pituitary-adrenal (HPA) axis dysfunction occurs frequently in critically ill humans and impacts survival. The prevalence and impact of HPA axis dysfunction in critically ill neonatal foals are not well characterized.


OBJECTIVE
(1) HPA axis dysfunction occurs in hospitalized neonatal foals, and is characterized by inappropriately low basal serum cortisol concentration or inadequate cortisol response to exogenous adrenocorticotropic hormone (ACTH); (2) hospitalized foals with HPA axis dysfunction have more severe disease and are less likely to survive than hospitalized foals with normal HPA axis function.


METHODS
Seventy-two hospitalized foals and 23 healthy age-matched foals.


METHODS
Basal ACTH and cortisol concentrations were measured and a paired low-dose (10 microg)/high-dose (100 microg) cosyntropin stimulation test was performed at admission in hospitalized foals. HPA axis dysfunction was defined as (1) an inappropriately low basal cortisol concentration or (2) an inadequate increase in cortisol concentration (delta cortisol) after administration of cosyntropin, with cut-off values for appropriate basal and delta cortisol concentrations determined from results obtained in healthy age-matched foals.


RESULTS
Forty-six percent of hospitalized foals had an inappropriately low basal cortisol concentration and 52% had an inadequate delta cortisol concentration after administration of the 100 microg dose of cosyntropin. An inadequate delta cortisol response to the high (100 microg) dose of cosyntropin was significantly correlated with shock and multiple organ dysfunction syndrome in hospitalized foals, and with decreased survival in a subgroup of septic foals.


CONCLUSIONS
HPA axis dysfunction occurs frequently in hospitalized neonatal foals, and negatively impacts disease severity and survival.
Hart
K A
KA
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, and Veterinary Teaching Hospital, Athens, GA 30602, USA. khart4@uga.edu
Slovis
N M
NM
Barton
M H
MH
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D003366:Cosyntropin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006734:Horse Diseases / Q000378:metabolism*; D006736:Horses; D006760:Hospitalization; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D008297:Male; D009102:Multiple Organ Failure / Q000662:veterinary; D010913:Pituitary-Adrenal System / Q000503:physiopathology*; D018805:Sepsis / Q000662:veterinary; D012769:Shock / Q000662:veterinary
D003366:Cosyntropin; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone