This chapter covers:
| Risk Group | Why They Are at Risk |
|---|---|
| Preterm infants | Developmental immaturity limits adrenal reserve — cortisol synthesis matures around 30 weeks |
| Critically ill neonates | Severe illness can create relative adrenal insufficiency (cortisol production adequate for basal state but not for acute stress) |
| Sepsis or shock | Cytokines, hypoperfusion, adrenal hemorrhage, or adrenal stress can impair cortisol response |
| Infants with recent prolonged steroid exposure | Exogenous steroids suppress the HPA axis and may require later testing and gradual tapering |
| Suspected CAH | Mineralocorticoid and glucocorticoid deficiency may cause shock and electrolyte abnormalities (see Chapter 4.1) |
Relative adrenal insufficiency = cortisol production is inadequate for the level of stress or illness (not necessarily absent).
Possible mechanisms:
| Sign | Practical Meaning |
|---|---|
| Hypoglycemia | May reflect inadequate cortisol response (cortisol promotes gluconeogenesis) |
| Hyponatremia + hyperkalemia | Suggests mineralocorticoid deficiency (aldosterone deficiency or CAH) |
| Hypotension or shock | Adrenal insufficiency impairs vascular tone and cardiovascular function |
| Poor response to volume and inotropes | Vasopressor-resistant hypotension should raise concern for adrenal insufficiency |
When an infant fails to respond to adequate volume resuscitation and vasopressors, adrenal insufficiency should be high on the differential. Do not wait for cortisol levels if the infant is unstable.
Consider hydrocortisone in:
Once clinically stable, wean hydrocortisone with the goal of stopping over 5–10 days, faster if blood pressure remains stable. Abrupt discontinuation after prolonged steroids risks rebound adrenal suppression.
| Clinical Situation | Hydrocortisone Dose |
|---|---|
| GA <32 weeks with vasopressor-resistant hypotension | 1 mg/kg IV every 8 hours |
| GA ≥32 weeks, mild to moderate stress | 20–50 mg/m²/day ÷ q6–8h; lower-end doses (20–30 mg/m²/day) may be given twice daily |
| GA ≥32 weeks, major stress or surgery | 100 mg/m²/day ÷ q6h |
| Known/suspected adrenal suppression with planned surgery | 50 mg/m² IV or IM 30–60 minutes before anesthesia, then 50 mg/m²/day ÷ q6–8h for at least 24 hours post-op |
| Step | Action |
|---|---|
| Step 1 | Give cosyntropin 1 microgram IV (low-dose) |
| Step 2 | Check cortisol at baseline (time 0) |
| Step 3 | Check cortisol at 30 minutes after ACTH |
| Step 4 | Check cortisol at 60 minutes after ACTH |
The low-dose ACTH stimulation test is more sensitive for detecting partial adrenal suppression than the standard high-dose (250 mcg) test used in CAH diagnosis. In infants with partial HPA suppression after steroid courses, the 1 mcg test is the preferred evaluation tool.
| Result | Interpretation |
|---|---|
| Baseline cortisol >10 mcg/dL | Supports normal adrenal function |
| Stimulated cortisol >18 mcg/dL | Supports normal adrenal response |
| Rise from baseline >10 mcg/dL | Supports normal adrenal response |
| Unclear response | Obtain pediatric endocrinology consultation |
Reference ranges for cortisol in neonates vary by lab, assay, and gestational age. When the response is borderline or the clinical picture is complex, involve endocrinology rather than relying solely on absolute values.
| Mistake | Better Action |
|---|---|
| Assuming all neonatal hypotension is volume-responsive | Consider adrenal insufficiency when hypotension is resistant to volume and inotropes |
| Missing electrolyte clues | Hyponatremia + hyperkalemia suggests mineralocorticoid deficiency — think CAH |
| Forgetting adrenal suppression after prolonged steroids | Test adrenal function 2–7 days after any steroid course longer than 2 weeks |
| Using a random cortisol alone to make all decisions | Baylor recommends stimulation testing and endocrinology input when the response is uncertain |
| Stopping hydrocortisone abruptly after significant illness | Wean after stabilization, aiming to stop over 5–10 days when clinically appropriate |
| Forgetting perioperative stress coverage | Give hydrocortisone before surgery in any infant with known or suspected adrenal suppression |
"Some sick or premature babies may not make enough cortisol, which is a stress hormone needed to maintain blood pressure, blood sugar, and salt balance."
"If the baby's blood pressure doesn't respond well to usual medicines, we may give hydrocortisone to support the body's stress response."
"If the baby has received steroid medicines for more than 2 weeks, we may test the adrenal gland afterward to make sure it can respond normally on its own. We gradually reduce the steroids rather than stopping them suddenly."