Cushing syndrome Flashcards
Symptoms of cushing syndrome due to high levels of stress hormone
Hypertension
Cardiac hypertrophy
Hyperglycaemia (T2DM)
Depression
Insomnia
Causes of cushing’s syndrome:
- Exogenous steroids
- Cushing’s disease (pituitary adenoma) - excessive ACTH release
- Adrenal adenoma (a hormone-secreting adrenal tumour)
- Pararoplastic Cushing’s
Paraneoplastic cushings
when excess ACTH released from a cancer
‘ectopic ACTH’
Small cell lung cancer is most common cause
Test of choice for diagnosing cushings
Dexamethasone supression test
Dexamethasone suppression test:
- Initially a low dose test - if low dose is normal –> Cushing’s is excluded
If abnormal - high dose test done to find the cause - Patient takes a dose of dexamethasone (a synthetic glucocorticoid) at night
- in the morning ACTH and cortisol are measured to see if the morning spike is suppressed
How much dexamethasone is used in low dose supression test?
1mg dexamethasone
Findings of low dose dexamethasone suppression test
Normal response:
- ↓ CRH, ↓ ACTH
- ↓ Cortisol
Abnormal (cushings syndrome)
- Cortisol not supressed
How much dexamethasone used in high dose suppression test?
8mg dexamethasone
Findings in high dose dexamethasone suppression test:
Pituitary adenoma:
- cortisol - suppressed
- ACTH - suppressed
Adrenal adenoma:
- Cortisol - not supressed
- ACTH - suppressed
Ectopic ACTH:
- Cortisol - not suppressed
- ACTH - not suppressed
Other investigations for cushing’s syndrome:
- 24hr urinary free cortisol
- can be used as alternative for diagnosing but nor for determining cause - FBC - raised WBC
- U&Es - hyperkalemia (if aldosterone is also secreted by adrenal adenoma)
- MRI brian - for pituitary adenoma
- CT Chest - SCLC
- CT Abdo - adrenal tumours
Treatment:
Treat underlying cause
- if pituitary adenoma - trans-sphenoidal removal
Otherwise surgical removal of adrenal/ ectopic tumour
If surgical removal of cause not possible:
- Remove both adrenals and offer steroid hormone replacement for life
