Treat Children with PAI Using Hydrocortisone with BSA-Based Dosing
STEP 1 — Gather Information
Confirm PAI diagnosis with low cortisol response to ACTH stimulation test and elevated ACTH; assess for aldosterone deficiency (renin, aldosterone); measure weight and height to calculate body surface area (BSA); review growth parameters, weight, blood pressure, and signs of glucocorticoid over- or under-replacement.
STEP 2 — Rule In / Rule Out
Is PAI biochemically confirmed (subnormal cortisol peak after 250 µg ACTH with elevated ACTH)?
- Yes → proceed to Step 3.
- No → consider secondary adrenal insufficiency, transient causes, or non‑adrenal etiologies; do not initiate glucocorticoid replacement pending further evaluation.
STEP 3 — Classify or Stratify
Determine if the child has concomitant aldosterone deficiency (elevated plasma renin with low aldosterone) requiring fludrocortisone replacement; if yes, plan mineralocorticoid therapy in addition to glucocorticoid dosing.
STEP 4 — Decide
Start hydrocortisone at 8 mg/m2/day divided into three or four doses (largest dose upon waking, subsequent doses spaced 4–6 hours apart, last dose not later than 4–6 hours before bedtime); adjust dose based on clinical wellbeing, growth velocity, blood pressure, and signs of over- (weight gain, Cushingoid features, hypertension) or under-replacement (fatigue, hypotension, hyperpigmentation, poor growth).
Clinical Guardrails / Mimics / Pitfalls
Do not use synthetic long‑acting glucocorticoids (e.g., dexamethasone, prednisolone) as first‑line in children; avoid dosing based solely on weight without BSA calculation; do not adjust dose based on plasma ACTH levels; avoid exceeding 20 mg/m2/day in infants or 15–17 mg/m2/day in adolescents without clear clinical indication; ensure patient/family education on stress dosing and emergency injection kit.
Concrete Clinical Example
A 4‑year‑old boy (weight 16 kg, height 100 cm, BSA ≈0.78 m2) with newly diagnosed PAI (low cortisol after 250 µg ACTH, high ACTH) and normal aldosterone. Starting hydrocortisone dose = 8 mg/m2/day × 0.78 m2 ≈ 6.2 mg/day, given as 2 mg at 08:00, 2 mg at 12:00, and 2.2 mg at 16:00. After two weeks, weight gain is appropriate and no Cushingoid signs; dose maintained.
Source: Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2016, DOI:10.1210/jc.2015-1710