Addison's and Cushing's Flashcards
What are the 3 layers of the adrenal gland?
What is secreted from each?
Zona glomerulosa → Mineralocorticoids → aldosterone
Zona fasciculata → Glucocorticoids → cortisol
Zona reticularis → Androgens
Medulla → epinephrine and norepinephrine
What is secreted from the Adrenal Medulla?
Catecholamines
Briefly explain the HPA axis in a healthy individual
What is Adrenal insufficiency?
Where the adrenal glands do not produce enough steroid hormones, particularly cortisol and aldosterone
What is primary adrenal insufficiency?
What is the specific name given to the disease?
Damage to the adrenal glands (most commonly autoimmune) resulting in reduced secretion of cortisol and aldosterone
Addison’s Disease
List 4 causes of primary adrenal insufficiency
- Autoimmune TB
- Haemorrhage
- Adrenoleukodystrophy
- Ketoconazole
What is secondary adrenal insufficiency?
A result of inadequate ACTH stimulating the adrenal glands, resulting in low cortisol release.
Due to loss or damage to the pituitary gland
List 4 causes of secondary adrenal insufficiency
- Surgery to remove a pituitary tumour
- Infection
- Loss of blood flow
- Radiotherapy
- Sheehan’s syndrome
What is Sheehan Syndrome?
Hypopituitarism caused by ischemic necrosis due to blood loss and hypovolemic shock during and after childbirth
Also known as postpartum pituitary gland necrosis
What is tertiary adrenal insufficiency?
Result of inadequate CRH release by the hypothalamus
What is the most common cause of tertiary adrenal insufficiency?
Explain why and state how this can be prevented
Long term oral steroids use (>3wks) causing suppression of the hypothalamus
When steroids are suddenly withdrawn the hypothalamus does not “wake up” fast enough and endogenous steroids are not adequately produced
Therefore, long term steroids should be tapered slowly to allow time for the adrenal axis to regain normal function
List 4 symptoms of hypoadrenalism
- Fatigue
- Cramps and weakness
- Abdominal pain
- Reduced libido
- Salt craving
- Anorexia, nausea, and vomiting, diarrhoea
- Weight loss
List 2 signs of hypoadrenalism
- Bronze hyperpigmentation (ACTH stimulates melanocytes to produce melanin)
- Hypotension (esp postural hypotension)
What investigations may you do if you suspect hypoadrenalism?
Highlight first line investigation
1. Early morning serum cortisol (8-9am) ☆
- Short synacthen test
- Serum ACTH
What is the test of choice to diagnose adrenal insufficiency
Explain this test
A short synacthen test (performed in the morning)
- Give synacthen (synthetic ACTH)
- Measure blood cortisol at baseline, 30 and 60mins after
- Synthetic ACTH will + healthy adrenals to produce cortisol
- Failure of cortisol to rise indicates 1o adrenal insufficiency (Addison’s)