Addison's Disease (Adrenal Insufficiency)

Question 1

What is the definition of Addison’s disease? [2]

Answer 1

a condition in which destruction of the adrenal cortex / results in glucocorticoid (cortisol), mineralocorticoid (aldosterone) and androgen (sex hormone) deficiency

Question 2

What is the pathophysiology of autoimmune adrenalitis? [4]

Answer 2

1. most common cause (80%) of Addison’s disease in the UK
2. there is destruction of the adrenal cortex / by adrenal antibodies (21-hydroxylase antibodies)
3. associated with other autoimmune diseases - type 1 diabetes mellitus, pernicious anaemia, Hashimoto’s thyroiditis

Question 3

What are other causes of Addison’s disease? [5]

Answer 3

1. tuberculosis (TB) - commonest cause worldwide
2. adrenal metastases - from lung, breast or renal cancer
3. long-term steroid use - will prevent ACTH release
4. opportunistic infections in HIV
5. adrenal haemorrhage/infarction

Question 4

What is the pathophysiology of secondary hypoadrenalism? [5]

Answer 4

1. issue with pituitary gland, not adrenal glands
2. commonest cause is iatrogenic, due to long term steroid therapy / leading to suppression of the pituitary-adrenal axis
3. other causes are rare and include hypothalamic-pituitary disease / leading to decreased ACTH production and therefore decreased cortisol
4. mineralocorticoid production remains intact

Question 5

What are the symptoms of Addison’s disease? [7]

Answer 5

1. lethargy, depression, low mood and self esteem
2. anorexia and weight loss
3. nausea and vomiting
4. abdominal pain
5. diarrhoea/constipation
6. pigmentation of skin/vitiligo
7. postural hypotension

Question 6

How can Addison’s disease be diagnosed? [6]

Answer 6

1. think of Addison’s disease in all who have unexplained abdominal pain or vomiting
2. blood tests
3. short ACTH stimulation test
4. ACTH levels
5. adrenal antibodies - 21-hydroxylase antibodies
6. chest/abdominal x-ray

Question 7

How can blood tests diagnose Addison’s disease? [6]

Answer 7

1. low Na+ and high K+ due to decreased aldosterone
2. low glucose due to decreased cortisol
3. high Ca2+
4. uraemia
5. anaemia
6. eosinophilia as lower cortisol = high white blood cells

Question 8

How can the short ACTH stimulation test diagnose Addison’s disease? [3]

Answer 8

1. measure plasma cortisol before and 30 mins after / giving tetracosactide (ACTH analogue)
2. Addison’s disease excluded if 30 min cortisol >550nmol/L

Question 9

How can ACTH levels diagnose Addison’s disease? [2]

Answer 9

9am ACTH is inappropriately high / >330ng/L

Question 10

How can chest/abdominal x-rays diagnose Addison’s disease? [2]

Answer 10

if there is a history of TB / look for upper zone fibrosis or adrenal calcification

Question 11

What is the treatment if a patient is seriously ill or hypotensive? [3]

Answer 11

1. IV hydrocortisone
2. IV 0.9% saline
3. glucose infusion if hypoglycaemic

Question 12

What is the general treatment for Addison’s disease? [3]

Answer 12

1. replace steroids 3 times a day to mimic circadian rhythm
2. oral hydrocortisone
3. oral fludrocortisone

Question 13

What advice is issued about steroid use? [4]

Answer 13

1. warn against abruptly stopping steroids
2. advise wearing a bracelet or carrying a card declaring steroid use
3. increase steroid dose before strenuous activity/exercise
4. double steroid dose in febrile illness, injury, or stress