Why Addisonian Crisis Is High-Yield
An Addisonian (adrenal) crisis is a genuine medical emergency with a specific, protocol-driven management that examiners love to test precisely because it is easy to get catastrophically wrong under pressure, delaying steroids while chasing a diagnostic cortisol level is a classic error that can kill the patient in a simulated scenario and will fail you the station. This topic sits naturally alongside DKA and thyroid emergencies as one of the "endocrine emergency" stations increasingly common in finals.
⚠️ Red Flag
The cardinal rule of this station: if adrenal crisis is suspected clinically, give hydrocortisone immediately, do not wait for confirmatory blood results. Treatment is never delayed for investigations in a genuine crisis.
Recognising Adrenal Crisis
Adrenal crisis occurs when cortisol production is insufficient to meet the body's needs, either due to established Addison's disease (primary adrenal insufficiency) decompensating under stress (infection, surgery, trauma), abrupt cessation of long-term steroids, or undiagnosed adrenal insufficiency unmasked by an acute illness.
🧠 Mnemonic
SHOCS for the clinical features of adrenal crisis:
- Shock (hypotension, often refractory to fluids alone)
- Hypoglycaemia
- Overwhelming fatigue/weakness
- Confusion or reduced consciousness
- Symptoms of the precipitant (fever from infection, vomiting, abdominal pain)
Additional clues:
- Hyponatraemia and hyperkalaemia (due to loss of mineralocorticoid effect)
- Nausea, vomiting, abdominal pain (can mimic an acute abdomen)
- Hyperpigmentation in known primary Addison's (buccal mucosa, palmar creases, scars), absent in secondary adrenal insufficiency (pituitary cause) as ACTH is low, not high
💎 Clinical Pearl
Why hyperpigmentation only occurs in primary adrenal insufficiency: ACTH and melanocyte-stimulating hormone (MSH) share the same precursor, pro-opiomelanocortin (POMC). In primary Addison's, low cortisol removes negative feedback, driving very high ACTH (and therefore MSH) production, causing pigmentation. In secondary adrenal insufficiency (pituitary/hypothalamic failure), ACTH is low, so pigmentation does not occur.
Risk Factors and Precipitants
- Known Addison's disease with an intercurrent illness, vomiting/diarrhoea (unable to absorb oral steroids), surgery, or trauma
- Abrupt withdrawal of long-term corticosteroids (any patient on more than 5mg prednisolone-equivalent for more than 3–4 weeks has a suppressed hypothalamic-pituitary-adrenal axis and is at risk)
- Bilateral adrenal haemorrhage (Waterhouse-Friderichsen syndrome, classically with meningococcal sepsis)
- Pituitary apoplexy (secondary adrenal insufficiency)
Immediate Management, Act Before Confirmation
🧠 Mnemonic
HIGH-F for immediate adrenal crisis management:
- Hydrocortisone 100mg IV/IM immediately
- IV fluids, 0.9% saline, rapidly for hypotension (1 litre over 30–60 minutes if shocked)
- Glucose, correct hypoglycaemia if present (IV dextrose)
- Hunt for and treat the precipitant (blood cultures, septic screen, treat infection)
- Further hydrocortisone, 50mg IV/IM every 6 hours (or continuous infusion) until stable, then convert to oral
💡 Tip
If asked "what if you're not sure it's adrenal crisis?", the correct answer is: take a cortisol sample if it doesn't delay treatment, but give hydrocortisone regardless. A random cortisol can still be interpreted afterwards (a low level supports the diagnosis; a very high level makes it less likely but does not exclude it in early presentation), and the harm of untreated adrenal crisis vastly outweighs the harm of a single empirical dose of hydrocortisone in someone who turns out not to have it.
Confirming the Diagnosis Later
Once the patient is stabilised, or in a non-emergency work-up of suspected adrenal insufficiency:
- Short Synacthen (ACTH stimulation) test: measure cortisol before and 30 minutes after synthetic ACTH; failure to rise above a threshold (typically >420–450 nmol/L, lab-dependent) confirms adrenal insufficiency.
- 9am cortisol: <100 nmol/L is highly suggestive of adrenal insufficiency; >450 nmol/L makes it unlikely.
- ACTH level: high in primary Addison's, low/inappropriately normal in secondary (pituitary) causes.
- Adrenal autoantibodies (21-hydroxylase antibodies) if autoimmune Addison's suspected.
Long-Term Management and Steroid Sick Day Rules
This is the counselling component examiners frequently pair with the emergency knowledge.
💎 Clinical Pearl
"Sick day rules": patients on long-term steroid replacement (or any patient on chronic steroids for other conditions) must be taught to double their oral steroid dose during any intercurrent illness with fever, and to switch to intramuscular hydrocortisone (which they should be prescribed and trained to self-administer) if vomiting, unable to take oral medication, or undergoing significant physical stress (major surgery, trauma).
Key counselling points:
- Never stop steroids abruptly, even when feeling better
- Carry a steroid emergency card and consider a medical alert bracelet
- Carry an emergency hydrocortisone injection kit if established on replacement therapy
- Increase dose for surgery, dental procedures, and significant physical stress, in consultation with the endocrine team
- Educate a partner or family member on how to give the emergency IM injection
⚠️ Red Flag
Never abruptly stop long-term corticosteroids in any patient, regardless of indication (asthma, COPD, rheumatoid arthritis, etc.), if they have been on a dose equivalent to prednisolone 5mg or more for over 3–4 weeks. This is a classic prescribing-safety exam point that overlaps directly with this topic.
Red Flags, Never Miss
⚠️ Red Flag
- Hypotension refractory to fluids in a patient with vague abdominal symptoms, weight loss, or hyperpigmentation
- Hyponatraemia with hyperkalaemia in an unwell patient (think adrenal insufficiency alongside renal causes)
- Any patient on long-term steroids presenting unwell who has missed doses or been unable to take oral medication
- Sudden severe headache with hypotension in a patient with known pituitary disease (pituitary apoplexy causing secondary adrenal crisis)
Frequently Asked Questions
"Why does adrenal crisis cause hyperkalaemia and hyponatraemia together?"
Aldosterone (a mineralocorticoid) normally promotes sodium reabsorption and potassium excretion in the distal nephron. In primary adrenal insufficiency, aldosterone deficiency causes sodium loss (hyponatraemia) and potassium retention (hyperkalaemia). This combination, alongside hypotension, is a strong clinical clue pointing to adrenal insufficiency rather than other causes of shock.
"Why is hyperpigmentation absent in secondary adrenal insufficiency?"
Because secondary adrenal insufficiency results from pituitary or hypothalamic failure, ACTH levels are low rather than elevated, so there is no excess melanocyte-stimulating hormone (which shares a precursor molecule with ACTH) to cause skin pigmentation.
"What would you tell a patient with Addison's disease going for minor dental surgery?"
They should double their usual oral hydrocortisone dose on the day of the procedure and for 24 hours afterwards if it's a minor procedure under local anaesthetic causing mild stress; for major surgery under general anaesthetic, they need IV hydrocortisone cover perioperatively, arranged in advance with the endocrine and anaesthetic teams.