What are the main clinical features of Addison's disease?

• lethargy, weakness, anorexia, nausea & vomiting, weight loss, 'salt-craving'
• hyperpigmentation (especially palmar creases), vitiligo, loss of pubic hair in women, hypotension, hypoglycaemia
• hyponatraemia and hyperkalaemia may be seen
• crisis: collapse, shock, pyrexia

What is the pathophysiology of Addison's disease?

Autoimmune destruction of the adrenal glands leading to primary hypoadrenalism

What is the commonest cause of primary hypoadrenalism in the UK?

Addison's disease

What are non-autoimmune causes of Primary hypoadrenalism?

• tuberculosis
• metastases (e.g. bronchial carcinoma)
• meningococcal septicaemia (Waterhouse-Friderichsen syndrome)
• HIV
• antiphospholipid syndrome

What are non-autoimmune causes of Secondary hypoadrenalism?

pituitary disorders (e.g. tumours, irradiation, infiltration)

What sign is seen in Addison's disease but not other causes of secondary adrenal insufficiency?

Primary Addison's is associated with hyperpigmentation whereas secondary adrenal insufficiency is not

What is the definite investigation Addison's disease?

ACTH stimulation test (short Synacthen test)

What is the management of Addisonian crisis?

• hydrocortisone 100 mg im or iv
• 1 litre normal saline infused over 30-60 mins or with dextrose if hypoglycaemic
• continue hydrocortisone 6 hourly until the patient is stable. No fludrocortisone is required because high cortisol exerts weak mineralocorticoid action
• oral replacement may begin after 24 hours and be reduced to maintenance over 3-4 days

What are the main causes of Addisonian crisis?

• sepsis or surgery causing an acute exacerbation of chronic insufficiency (Addison's, Hypopituitarism)
• adrenal haemorrhage eg Waterhouse-Friderichsen syndrome (fulminant meningococcemia)
• steroid withdrawal