History/Exam: Addison's Disease Flashcards
What is Addison’s disease?
A rare autoimmune endocrine disorder causing primary adrenal insufficiency. Autoantibodies are directed against the adrenal glands resulting in destruction of the adrenal cortex and decreased cortisol release.
Adrenal insufficiency can be divided into primary and secondary.
What are some causes of 1ary adrenal insufficiency?
- Addison’s disease (80%)
- Adrenal adenomas
- HIV
- TB
- Congenital adrenal hyperplasia
What is 2ary adrenal insufficiency?
Due to the impairment of the pituitary gland to produce ACTH.
What is 1ary adrenal insufficiency?
Due to a problem within the adrenal glands causing impairment of cortisol production.
What are the 3 causes of 2ary adrenal insufficiency?
1) Exogenous steroid use (most common)
2) Pituitary adenoma
3) Hypothalamic tumour.
What is the most common cause of 2ary adrenal insufficiency?
Exogenous steroid use
What symptoms should you ask about for Addison’s disease?
Note - these are vague and are due to low circulating levels of cortisol.
- Tiredness
- Weight loss
- N&V
- Abdo pain & diarrhoea
- Weakness
- Confusion
- Syncope, dizziness on standing
- Joint pains
- Myalgia
- Fever
- Menstrual disturbance
- Obvious skin changes (hyperpigmentation)
What conditions should you specifically ask about in PMH and FH for Addison’s?
Associated autoimmune conditions:
- vitiligo
- thyroid disease
- T1D
What should you include in SH iin Addison’s?
- Travel
- TB risk assessment
- HIV risk assessment
Possible examination findings in 1ary adrenal insufficiency?
1) Widespread hyperpigmentation
2) Women may have a loss of axillary or pubic hair
3) BP may be low (note - if BP is raised this would almost exclude a diagnosis of Addison’s disease)
4) Look for evidence of other associated autoimmune conditions e.g. vitiligo
5) Look for medicAlert bracelet or necklace
What causes hyperpigmentation in 1ary adrenal insufficiency?
It is caused by the stimulant effect of excess adrenocorticotrophic hormone (ACTH) on the melanocytes to produce melanin
Hyperpigmentation in 1ary vs 2ary adrenal insufficiency
1ary –> hyperpigmentation present (due to increased ACTH in response to low cortisol)
2ary –> no hyperpigmentation (due to low ACTH due to pituitary problem)
Where is hyperpigmentation particularly evident in Addison’s?
- palmar creases
- pressure areas (e.g. elbows)
- buccal mucosa
- skin creases
- previous surgical scars
- light-exposed areas
How is BP affected in Addison’s?
Hypotension
What are the 3 autoimmune conditions assoicated with Addison’s?
1) Vitiligo (look for depigmented skin)
2) Autoimmune thyroid disease
3) Type 1 diabetes
What are the 7 investigations would you do for suspected adrenal insufficiency?
1) BP
2) Blood glucose
3) FBC
4) U&Es
5) 9am cortisol
6) Short synacthen test
7) Serum ACTH
What blood tests can be done in Addison’s?
1) FBC
2) U&Es
3) LFTs
4) Plasma renin and aldosterone
5) Adrenal autoantibodies
6) TFTs
7) Serum ACTH
What may FBC show in Addison’s?
Normocytic anaemia, lymphocytosis or associated eosinophilia
What may U&Es show in Addison’s?
- hyponatraemia
- hyperkalaemia
- occasionally hypercalcaemia
What 9am cortisol level is indicative of adrenal insufficiency?
<100
What 9am cortisol level is a grey area and would need a short synacthen test to further investigate?
100-400
What 9am cortisol level is indicative of adrenal sufficiency?
> 400
What is the short synacthen test?
The test of choice for diagnosing adrenal insufficiency.
1) Guve dose of synacthen (synthetic ACTH)
2) Blood cortisol is checked before, 30 and 60 minutes after dose
3) A failure of cortisol to double indicates 1ary adrenal insufficiency
What 2 conditions does a failure of cortisol to double in a short synacthen test indicate?
1) Primary adrenal insufficiency (Addison’s disease)
2) Very significant adrenal atrophy after a prolonged absence of ACTH in secondary adrenal insufficiency
Adrenal autoantibodies should be measured as these are positive in around 70% of cases of Addison’s disease.
What 2 autoantibodies may be present in autoimmune adrenal insufficiency?
1) Adrenal cortex antibodies
2) 21-hydroxylase antibodies
ACTH can be measured directly.
Describe ACTH level in 1ary vs 2ary adrenal insufficiency
1ary - high
2ary - low
Why should you check TFTs in suspected Addison’s?
As there is a high incidence of associated autoimmune thyroid disorders
What is treatment for Addisonian crisis?
1) Admission
2) Hydrocortisone 100mg (IM or IV)
3) 1 litre 0.9% saline infused over 30-60 mins or with dextrose if hypoglycaemic
4) Continue hydrocortisone 6 hourly until the patient is stable
5) Oral replacement may begin after 24 hours and be reduced to maintenance over 3-4 days
Why is hydrocortisone given in adrenal crisis?
As has both mineralocorticoid and glucocorticoid actions
