Cushing's Flashcards
What is Cushing’s syndrome?
Endocrine disorder with elevated cortisol levels in the blood due to hyperactivity of the adrenal cortex.
What is Cushing’s disease?
Pituitary adenoma secreting ACTH produces adrenal hyperplasia
What is the characteristic appearance of patients with Cushing’s syndrome?
- Central obesity
- Dorso-cervical fat pad
- Moon face (roundness in the face)
- Thin arms & legs
- Red cheeks
What is the most common cause of Cushing’s Syndrome?
Prescribed glucocorticoids
What are the endogenous causes of Cushing’s syndrome?
- Benign ACTH-secreting pituitary adenoma (Cushing’s disease)
- Adrenal adenoma producing excess cortisol (Adrenal Cushing’s)
- Ectopic secretion non pituitary-adrenal tumours producing ACTH / CRH (e.g. small cell lung tumour)
What 3 features are suggestive of ectopic ACTH as a cause?
- Hypokalaemia
- History of smoking
- Weight loss
What are the signs & symptoms of excess cortisol (Cushing’s syndrome)?
- Hyperglycaemia w/ polydipsia & polyuria (“steroid diabetes”)
- Thin arms / legs & muscle weakness
- Weight gain
- Moon-shaped face, buffalo hump, truncal obesity
- Purple striae on lower abd, upper arms and thighs
- Easy bruising
- Hypertension
- Acne
- Bacterial infections
- Back pain
What are signs of excess cortisol (Cushing’s Syndrome)?
What medications can cause Cushing’s-like signs & symptoms?
Glucocorticoids (Steroids):
- Hydrocortisone
- Prednisolone
What is the prognosis for untreated Cushing’s disease?
Associated with significant morbidity
5 year mortality around 50%
What is Pseudo-Cushing’s?
Cushingoid appearance typically due to excessive alcohol consumption or severe depression.
causes false positive dexamethasone suppression test or 24 hr urinary free cortisol
insulin stress test may be used to differentiate
What 2 investigations are typically used to confirm Cushing’s? State what results you would expect in a case of Cushing’s.
- Overnight dexamethasone suppression test
- > 50 nmol/L
- 24hr Urinary free cortisol
- Elevated
What investigations can be used to localise the cause of Cushing’s Syndrome?
- 9am & Midnight plasma ACTH & cortisol levels
- Low- & high-dose dexamethasone suppression tests
- To localise the pathology resulting in Cushing’s syndrome
- CRH stimulation
- Petrosal sinus sampling
You conduct a 9am & Midnight plasma ACTH & cortisol levels test, following which ACTH is suppressed. What does this mean?
Non-ACTH dependent cause more likely
e.g. Adrenal adenoma, steroids
A patient presents with Cushingoid features aswell as significant/accelerated hirsutism. What does this suggest?
Adrenal tumour
What results would you expect from a 9am / midnight plasma ACTH test done on a patient with an adrenal tumour? & why?
- Low ACTH
High cortisol supresses ACTH secretion via negative feedback
What investigation can be used to distinguish between pituitary and ectopic causes of Cushing’s?
How do the results differ between the causes?
CRH test:
- Pituitary cause = Exaggerate rise in ACTH & cortisol
- Ectopic cause = No response
A patient with Cushing’s undergoes Dexamethasone Suppression Test (low & high). Cortisol levels are suppressed by high dose dexamethasone but not by low dose, what does this suggest?
Cushing’s disease
A patient with Cushing’s undergoes Dexamethasone Suppression Test (low & high). Cortisol levels are not suppressed by high dose or low dose dexamethasone, what does this suggest?
Ectopic secretion of ACTH
(e.g. small cell lung cancer)
What is petrosal sinus sampling of ACTH used for?
May be needed to differentiate between pituitary and ectopic ACTH secretion
How are adrenal tumours managed?
Laparoscopic adrenalectomy
How is ectopic ACTH managed?
- Appropriate treatment of underlying malignancy
- Medical control of cortisol levels
How is Cushing’s disease (pituitary adenoma) managed?
- Trans-sphenoidal removal of pituitary adenoma
- Metyrapone / Ketoconazole
- Radiotherapy (may help)
