Executive summary
- Think adrenal insufficiency in people with fatigue, weight loss, postural symptoms, nausea, abdominal pain, salt craving, hyperpigmentation, unexplained hyponatraemia, recurrent hypoglycaemia, or a relevant steroid-exposure history.
- Initial test: offer an 8 am to 9 am serum cortisol for people aged 1 year and over with suspected adrenal insufficiency.
- Thresholds: <150 nmol/L = likely adrenal insufficiency and endocrinology referral; 150–300 nmol/L = uncertain, repeat/seek advice; >300 nmol/L = adrenal insufficiency very unlikely (with modern immunoassays).
Routine treatment
- Primary adrenal insufficiency: replace glucocorticoid and mineralocorticoid. Adults are usually treated with hydrocortisone 15–25 mg/day in divided doses plus fludrocortisone 50–300 micrograms/day as needed.
- Secondary/tertiary adrenal insufficiency: glucocorticoid replacement only. Adults are usually treated with hydrocortisone 15–25 mg/day in 2–3 divided doses.
- Alternative glucocorticoid: prednisolone 3–5 mg/day may be used in selected adults if multiple daily hydrocortisone doses are impractical.
- Education matters: give advice on daily dosing, sick-day rules, crisis management, and emergency steroid identification.
Sick-day rules and adrenal crisis
- During significant physiological stress, NICE advises at least 40 mg oral hydrocortisone daily in 2–4 divided doses or at least 10 mg oral prednisolone daily in 1–2 divided doses until the acute illness or trauma has resolved.
- If adrenal crisis is suspected, treat first: give 100 mg hydrocortisone IM/IV immediately, start urgent transfer, and arrange fluid resuscitation. Do not delay treatment while waiting for labs.
- Emergency kit: people with primary or secondary adrenal insufficiency should have access to emergency hydrocortisone and know how to use it.
- Important prescribing trap: random cortisol tests are not the preferred screening test; the 8–9 am sample is the NICE starting point.
Frequently asked questions
When should I test cortisol in suspected adrenal insufficiency?
Use an 8 am to 9 am serum cortisol in people aged 1 year and over. NICE advises against using random daytime cortisol as the first-line screening test.
What serum cortisol level is strongly concerning?
Below 150 nmol/L should prompt recognition that adrenal insufficiency may be present, endocrinology referral, and consideration of treatment. If the person is acutely unwell, manage as possible adrenal crisis.
What is the emergency dose for suspected adrenal crisis in adults?
Hydrocortisone 100 mg IM or IV immediately, alongside urgent hospital transfer and fluids.
Transparency
This page is an educational, clinician-written summary of publicly available NICE guidance intended for trained healthcare professionals. It uses original wording (not copied text) and should be used alongside the full NICE source, local pathways, and clinical judgement. Doses provided are for general reference; always check the BNF/SPC.