Glucocorticoid Replacement Pregnancy: Compatible — cortisol is essential; dose requirements increase in third trimester; cover delivery with IV hydrocortisone 100 mg

Hydrocortisone (Oral Replacement)

Brand names: Plenadren (modified release), Efmody (dual-release), hydrocortisone (standard)

Adult dose

Dose: Adrenal insufficiency: 15–25 mg/day in 2–3 divided doses (e.g., 10 mg on waking + 5 mg at midday + 5 mg early afternoon). Congenital adrenal hyperplasia: 10–20 mg/m²/day.

Route: Oral

Frequency: BD–TDS (mimic diurnal cortisol rhythm — larger dose in morning)

Max: 30 mg/day (physiological replacement); higher doses in CAH

Immediate-release preferred for physiological rhythm. Plenadren (MR): OD, less diurnal variation. Sick day rules essential: double dose during illness, triple if >38°C or vomiting (seek emergency injection pack).

Paediatric dose

Route: Oral

Frequency: TDS

Max: As per BSP/BSPED protocol based on surface area

Concentration: 10 mg tablet; 2 mg/mL suspension mg/m²/day/ml

CAH in children: 8–10 mg/m²/day in 3 equal doses. Puberty may increase requirements. Monitor for over-replacement (growth suppression).

Dose adjustments

Renal

No dose adjustment required

Hepatic

Increase dose in severe hepatic impairment (altered cortisol metabolism)

Clinical pearls

Sick day rules: every patient must have written instructions — double dose for ≥48h minor illness; triple if >38.5°C; IV hydrocortisone 100 mg IM injection if unable to take orally (emergency kit)
Plenadren (modified-release): OD dosing may improve metabolic parameters; preferred by some patients
Timing is important: ideally take first dose on waking (within 30 min), not at fixed clock time, to mimic natural cortisol peak
Annual review: check for over/underreplacement signs — weight, BP, pigmentation (primary AI)

Contraindications

Systemic fungal infection without antifungal cover
Live vaccines (doses suppressing immunity)

Side effects

Overreplacement: Cushing features, weight gain, hypertension
Underreplacement: fatigue, nausea, hypotension, hypoglycaemia
Adrenal crisis if suddenly stopped or sick day rules not followed

Interactions

Rifampicin — dramatically increases cortisol metabolism (double replacement dose)
Oestrogens — increase cortisol-binding globulin, may need higher doses in women on OCP
Phenytoin/carbamazepine — increased hydrocortisone metabolism

Monitoring

Clinical assessment (weight, BP, energy, pigmentation)
24-hour urinary free cortisol (intermittently)
HbA1c and blood pressure for over-replacement
Growth in children (height velocity)

Reference: BNFc; BNF; Society for Endocrinology Addison's guidelines; BSPED CAH guidelines; Arlt et al Lancet 2003. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways