Addison's disease

Question 1

Pathophysiology?

Answer 1

Autoimmune destruction of the adrenal glands leading to primary hypoadrenalism (resulting in reduced cortisol and aldosterone)

Question 2

Symptoms?

Answer 2

• lethargy
• weakness
• anorexia
• nausea & vomiting
• weight loss
• ‘salt-craving’
• hyperpigmentation (especially palmar creases)
• vitiligo
• loss of pubic hair in women
• hypotension
• hypoglycaemia

Question 3

What electrolyte abnormalities may be seen and how often are they seen?

Answer 3

• hyperkalaemia
• hyponatraemia
• hypoglycaemia
• metabolic acidosis

Associated electrolyte abnormalities are seen in around one-third of undiagnosed patients:

Question 4

Symptoms of an Addisonian crisis?

Answer 4

• collapse
• shock
• pyrexia

Question 5

Other causes of hypoadrenalism? (primary causes)

Answer 5

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

Question 6

Other causes of hypoadrenalism? (secondary causes)

Answer 6

• pituitary disorders (e.g. tumours, irradiation, infiltration)
• Exogenous glucocorticoid therapy

Question 7

What symptom is associated with primary Addison’s which does not occur in secondary adrenal insufficiency?

Answer 7

Hyperpigmentation

Question 8

1st line investigation? How does this work?

Answer 8

ACTH stimulation test (short Synacthen test).
Plasma cortisol is measured before and 30 minutes after giving Synacthen 250ug IM and a poor rise is indicative of Addison’s disease.

Question 9

What other test can be performed if an ACTH stimulation test is not readily available?

Answer 9

9am serum cortisol.

Question 10

What does a >500nmol/l cortisol result mean in a 9am serum cortisol test?

Answer 10

Addison’s very unlikely

Question 11

What does a <100nmol/l cortisol result mean in a 9am serum cortisol test?

Answer 11

Definitely abnormal

Question 12

What does a 100-500nmol/l cortisol result mean in a 9am serum cortisol test?

Answer 12

Should prompt a ACTH stimulation test

Question 13

Treatment?

Answer 13

Patients take a combination of:
• hydrocortisone: usually given in 2 or 3 divided doses. Patients typically require 20-30 mg per day, with the majority given in the morning dose
• fludrocortisone

Question 14

What patient education is important?

Answer 14

• emphasise the importance of not missing glucocorticoid doses
• consider MedicAlert bracelets and steroid cards
• discuss how to adjust the glucocorticoid dose during an intercurrent illness

Question 15

How to manage an intercurrent illness?

Answer 15

The glucocorticoid dose should be doubled

Question 16

Causes for an Addisonian crisis?

Answer 16

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

Question 17

Management of an Addisonian crisis?

Answer 17

• 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