Steroids, steroid precursors, and neuroactive steroids in critically ill equine neonates.
Authors: Dembek K A, Timko K J, Johnson L M, Hart K A, Barr B S, David B, Burns T A, Toribio R E
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Dysfunction of the hypothalamic-pituitary-adrenal axis (HPAA) in critically ill foals has long been recognised as a prognostic indicator, yet previous research has narrowly focused on cortisol alone, overlooking the broader endocrine response to systemic disease. Dembek and colleagues examined blood concentrations of ACTH, cortisol, and seven additional steroid hormones in 326 hospitalised foals, stratifying them by sepsis status and predicted survival probability to characterise the complete adrenal steroid response to critical illness. Septic foals exhibited significantly elevated ACTH, cortisol, progesterone, and their precursors (17α-OH-progesterone, pregnenolone, androstenedione) alongside disproportionately high ACTH-to-steroid ratios compared to sick non-septic and healthy controls—a pattern termed ACTH-cortisol imbalance (ACI)—whilst foals with the poorest survival prognosis demonstrated further elevation in ACTH, aldosterone, and progesterone. Most notably, progesterone concentrations above 23.5 ng/mL predicted non-survival with 75% sensitivity and 72% specificity, and foals with DHEAS levels between 0.4–5.4 ng/mL were 2.5 times more likely to display ACI, making these markers potentially valuable adjuncts to cortisol assessment. For equine practitioners, measuring progesterone and DHEAS alongside traditional cortisol and ACTH evaluations may improve early identification of foals with critical HPAA dysfunction and guide prognostic counselling, though further prospective validation in clinical settings remains warranted.
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Practical Takeaways
- •In critically ill foals, measuring progesterone and DHEAS alongside cortisol provides better prognostic information for predicting survival and identifying HPAA dysfunction than cortisol alone
- •A progesterone threshold of 23.5 ng/mL can be used clinically as a cutoff to help guide prognosis and treatment intensity decisions in hospitalised neonatal foals
- •ACTH-to-cortisol ratio imbalance and elevated multiple steroid precursors suggest severe illness severity and warrant aggressive supportive care and investigation for sepsis
Key Findings
- •Septic foals demonstrated significantly elevated ACTH, cortisol, progesterone, 17α-OH-progesterone, pregnenolone, and androstenedione concentrations compared to sick non-septic and healthy foals (P<0.01)
- •DHEAS concentrations of 0.4-5.4 ng/mL were associated with 2.5-fold increased odds of ACTH-cortisol imbalance, a marker of HPAA dysfunction
- •Progesterone concentration ≥23.5 ng/mL predicted non-survival with 75% sensitivity and 72% specificity in hospitalised foals
- •Foals with poor survival prognosis (Group 1: 3-18% survival likelihood) had higher ACTH, aldosterone, progesterone, and cortisol concentrations than foals with better outcomes (P<0.01)