Select glucocorticoid regimen for ACTHD
STEP 1 — Gather Information
Confirm ACTHD diagnosis via appropriate dynamic testing (e.g., insulin tolerance test or low-/high-dose ACTH stimulation test) per guideline 6.3; obtain baseline weight, height, and body surface area; assess for concurrent illnesses or planned procedures requiring stress dosing; review current medications that may affect cortisol metabolism (e.g., enzyme-inducing antiepileptics).
STEP 2 — Rule In / Rule Out
Is ACTHD biochemically confirmed? If yes, proceed to glucocorticoid replacement planning; if no, reconsider diagnosis and evaluate for other causes of fatigue, hypotension, or hyponatremia (e.g., primary adrenal insufficiency, sepsis, medication effect) before initiating steroids.
STEP 3 — Classify or Stratify
Calculate physiologic hydrocortisone dose based on body surface area: typical pediatric replacement is 8–10 mg/m²/day divided into two or three doses (e.g., higher dose in the morning). Adjust for age/weight if BSA unavailable: approximate 0.15–0.2 mg/kg/dose TID.
STEP 4 — Decide
Prescribe calculated hydrocortisone regimen with standard stress coverage: double or triple the daily dose during mild illness, fever, or minor stress; administer parenteral hydrocortisone (50–100 mg/m² bolus then continuous infusion or q6h dosing) for major stress, surgery, or adrenal crisis; provide emergency injectable kit and medical alert identification.
Clinical Guardrails / Mimics / Pitfalls
Do not confuse ACTHD with primary adrenal insufficiency (which requires mineralocorticoid replacement); avoid over-replacement to prevent iatrogenic Cushingoid features, weight gain, or bone loss; remember that enzyme-inducing antiepileptics may increase hydrocortisone clearance, necessitating higher doses; never abruptly discontinue glucocorticoids without taper; stress dosing is essential during illness, surgery, or trauma to prevent adrenal crisis.
Concrete Clinical Example
A 12-year-old female survivor of craniopharyngioma treated with 36 Gy cranial radiation presents with fatigue and hypotension; ACTHD confirmed by low-dose ACTH stimulation test. Weight 38 kg, BSA ~1.2 m². Prescribe hydrocortisone 10 mg/m²/day = 12 mg total daily, divided as 6 mg AM, 3 mg early afternoon, 3 mg late afternoon. For fever >38°C, double dose to 24 mg/day divided TID. Provide emergency hydrocortisone injection card.
Source: Hypothalamic Pituitary and Growth Disorders in Survivors of Childhood Cancer: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2018, https://doi.org/10.1210/jc.2018-01175