Plasma adrenocorticotropin, cortisol, and adrenocorticotropin/cortisol ratios in septic and normal-term foals.
Authors: Gold J R, Divers T J, Barton M H, Lamb S V, Place N J, Mohammed H O, Bain F T
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary Understanding the endocrine response to sepsis in neonatal foals remains clinically important, yet the hypothalamic-pituitary-adrenal (HPA) axis function in these critically ill patients has been poorly characterised. Researchers measured plasma ACTH and cortisol concentrations in 46 septic foals (≤14 days old) admitted to referral centres and 28 age-matched healthy controls, collecting blood samples within 12 hours of admission and assessing survival outcomes over the treatment period. Septic foals demonstrated significantly elevated ACTH, cortisol, and ACTH/cortisol ratios compared to healthy foals—a response consistent with the expected neuroendocrine activation during critical illness—but a particularly striking finding emerged when non-surviving septic foals showed significantly higher ACTH/cortisol ratios than those that survived to discharge. The elevated ratio in non-survivors suggests relative adrenocortical insufficiency or failure of the adrenal gland to respond appropriately to ACTH stimulation during sepsis, potentially indicating HPA axis dysfunction at the adrenal level that may contribute to mortality risk. Clinicians should consider that poor adrenal responsiveness, rather than absolute hormone deficiency, may characterise the most severe septic cases and warrant investigation of whether targeted endocrine support could improve outcomes in neonatal foal sepsis.
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Practical Takeaways
- •Elevated ACTH/cortisol ratios in septic foals may indicate worse prognosis and adrenal insufficiency; consider this as a potential prognostic indicator when managing neonatal sepsis
- •Neonatal septic foals show expected endocrine stress response with higher cortisol and ACTH, but nonsurvivors have disproportionately elevated ACTH suggesting impaired adrenal responsiveness
- •Measurement of ACTH/cortisol ratio could help identify critically ill foals with compromised adrenal function early in hospitalization
Key Findings
- •Septic foals had significantly higher mean ACTH, cortisol, and ACTH/cortisol ratios compared to normal control foals
- •Cortisol concentrations in control foals did not vary with age
- •The mean ACTH/cortisol ratio was significantly higher in septic nonsurviving foals (n=18) compared to septic surviving foals (n=28)
- •Elevated ACTH/cortisol ratio in nonsurviving septic foals suggests adrenal gland dysfunction in critically ill neonates