Cushing's syndrome (+ disease) Flashcards
what is the role of cortisol in the body?
Increases glucose in the blood stream.
inhibits bone formation.
Increases resistance to insulin.
increases blood pressure.
What is the cortisol releasing pathway?
Hypothalamus - Cortisol releasing hormone.
Anterior pituitary - Adrenocorticotropic hormone (ATH).
Adrenal gland - Cortisol.
What is cushings syndrome?
The signs and symptoms that occur due to increased cortisol levels in the body.
What is cushings disease?
Caused specifically by a pituitary adenoma secreting too much ACTH.
What are the features of Cushing syndrome?
Moon face Buffalo hump Abdominal striae Hirtuism Proximal muscle wasting Abdominal obesity Flushed face Acne Thin skin Hypertension Hyperglycaemia Type 2 diabetes insomnia depression cardiac hypertrophy osteopenia or osteoporosis easy bruising poor skin healing
what are the ACTH dependent causes of cushings syndrome?
80% Pituitary adenoma
Ectopic ACTH producing tumour
What is the most common cause of an ectopic ACTH secreting tumour?
Small cell lung cancer
What are the ACTH dependent causes of cushings syndrome?
Adrenal adenoma
Adrenal carcinoma
External steroids
What is paraneoplastic cushings syndrome?
When an ectopic tumour (like in small cell lung cancer) starts to secrete excess ACTH.
what are the tests used to diagnose cushings syndrome?
Dexamethasone test (low dose + high dose). 24 hr urinary free cortisol. FBC. MRI brain - pituitary adenoma Chest CT - small cell lung cancer Abdominal CT - adrenal tumour
What is the low dose dexamethasone test?
1g of dexamethasone is given at night.
USUALLY the dexamethasone should cause negative feedback and should cause low levels of ACTH and cortisol.
Cortisol and ACTH levels are measured the next morning.
What do the low and high dose dexamethasone tests show?
Low dose - shows if you have cushings syndrome or not.
High dose - show the cause of cushings syndrome.
If the low dose dexamethasone test is abnormal, what is done next?
High dose dexamethasone test.
8g of dexamethasone is given and ACTH and cortisol levels are measured the next day.
What do the different high dose dexamethasone results show?
Suppressed cortisol and ACTH - in pituitary adenoma.
raised cortisol and suppressed ACTH - in pituitary adenoma.
Cortisol and ACTH still high - ectopic ACTH producing tumour.
What will the dexamethasone test results show in cushings DISEASE?
Low dose - cortisol and ACTH still high.
High dose - ACTH and cortisol will be low.
