cushing syndrome Flashcards
what is cushing’s syndrome?
prolonged high levels of glucocorticoids in the body
what are the two groups of corticosteroid hormones?
- glucocorticoids eg cortisol
- mineralcorticoids eg aldosterone
what exogenous substance often causes cushings syndrome?
- prolongued use of exogeous corticosteroids
what features could be found upon inspection in someone with cushings syndrome?
- round face (moon face)
- central obesity
- abdominal strae (stretch marks)
- enlarged fat pad on the upper back (known as buffalo hump)
- proximal limb muscle wasting (difficulty standing from a sitting position without using their arms)
- male pattern facial hair in women (hirsutism)
- easy bruising and poor skin healing
- hyperpigmentation of the skin
what are some metabolic effects which cushing syndrome might cause in a patient? (5)
- hypertension
- cardiac hypertrophhy
- type 2 diabetes
- dyslipideamia
- osteoporosis
what are some mental health effects which cushings syndrome might cause in a patient?
- anxiety
- depression
- insomnia
- rarely psychosis
what are the causes of Cushings syndrome and the nemonic?
CAPE
C - cushings disease - a pituitary adenoma (inc ACTH which in turn inc cortisol)
A - adrenal adenoma (inc cortisol)
P - paraneoplastic syndrome (ectopic ACTH - inc cortisol
E - exogenous steroids
paraneoplastic syndrome is a cause of Cushing’s syndrome, what is this?
- when ACTH is released from the tumour somewhere other than the pituitary gland
- this is called ectopic ACTH
- common in small lung cancer
- this stimulates excessive cortisol release from the adrenal glands
what is a dexamethasone suppression test?
- test to diagnose cushings syndrome
- not used for cushings syndrome caused by
how does a dexamethasone suppression test work?
- usually the hypothalamus releases CRH
- in turn stimulates the pituitary glands to secrete ACTH
- in turn stimulates the adrenal glands to secrete cortisol
- when dexamethasone is introduced, it has a negative feedback effect on CRH which should therefore reduce the ACTH and therefore lower the cortisol which is secreted
- in instances of cushings disease, cortisol levels wont drop
how is a pituitary tumour, exogenous steroids or ectopic ACTH measured?
- ACTH is measured directly
- it is suppressed due to negative feedback on the pituitary from cortisol coming from the adrenal tumour or exogenous steroid
what is an alternative to the dexamethasone suppression test?
- 24-hour urinary free cortisol
- doesn’t indicate underlying cause however
what other investigations can be conducted to assess cushings syndrome?
- full blood count - may show high white blood cell count
- U&Es - low potassium if an adrenal adenoma is also secreting aldosterone
-MRI - pituitary adenoma - CT chest scans for small lunch cancers
- abdominal CT for adrenal tumours
what are the different treatment options for cushings syndrome?
- trans sphenoidal (through nose) removal of the pituitary adenoma
- surgical removal of adrenal tumour
- surgical removal of the tumour producing ectopic ACTH
- where these arent possible, can surgically remove both adrenal glands and give the patient life-long steroid replacement therapy
what is nelsons syndrome and what are some symptoms?
- development of ACTH-producing pituitary tumours after adrenal glands have been removed due to a alack of cortisol and negative feedback
symptoms:
- bitemporal hamianopia
- skin pigmentation
- lack of other pituitary hormones
