Longitudinal assessment of adrenocortical steroid and steroid precursor response to illness in hospitalized foals.

This study investigates the concentration of various steroids and their precursors in the blood of young foals, less than 4 days old, who are critically ill versus healthy foals. The research found that levels of these hormones were higher in sick foals on admission and remained high throughout their hospital stays. The findings suggest that a high concentration of certain hormones such as progesterone might be a reliable indicator of poor recovery and mortality in sick foals.

Research context

• Sepsis is a huge concern and a leading cause of morbidity and mortality in newborn foals.
• Relative Adrenal Insufficiency (RAI), an insufficient cortisol response to stress, has been linked to partial causes of sepsis in newborn foals.
• The adrenal gland produces a number of important steroids and their precursors like cortisol, aldosterone, androgens, and progestogens.
• Nonetheless, no comprehensive evaluation has been carried out to ascertain the concentration of these hormones during hospitalization and their relation with disease severity and mortality in critically ill foals.

Research methodology

• Four categories of foals aged less than 4 days were established: healthy, septic, sick non-septic, and premature. The categorization was based on physical exams, medical history, and laboratory data.
• Blood samples were collected on admission (0 h), 24 h, and 72 h after admission.
• The concentration of steroids and ACTH (Adrenocorticotropic hormone) in the blood samples was measured using immunoassays.
• The researchers calculated the Area Under the Curve over 72 hours (AUC0-72h) of hospitalization for each hormone.

Research findings

• At 0 hours and over the following 72 hours of hospitalization, levels of cortisol, aldosterone, progesterone, pregnenolone, DHEAS (Dehydroepiandrosterone Sulfate), and 17 α-hydroxyprogesterone were significantly higher in both premature and septic foals compared to the healthy ones.
• The admission Plasma ACTH levels of septic and premature foals were significantly higher compared to the healthy ones.
• Critically ill neonatal foals exhibited a stress response signified by elevated concentrations of cortisol and steroid precursors upon admission.
• Healthier foals saw a rapid decrease in steroid concentration.
• In contrast, upheld high levels of progestogen and androgen were linked to lack of disease improvement and a poor outcome.

Research conclusion and application

• The research concludes that the progesterone (AUC0-72h) cut-off value above which non-survival could be reliably predicted in hospitalized foals was 1,085 ng/mL/h (with 82% sensitivity and 77% specificity).
• This observation can be valuable in evaluating the wellness status of hospitalized foals, helping to tailor treatments and manage expectations accordingly.
• The findings of this study contribute to a better understanding of the relationships between adrenal hormones and illness in neonatal foals, which may be useful in predicting illness severity and outcomes.