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
what is metyrapone and when is it used?
- reduces the production of cortisol in the adrenals
- occasionally used in the treatment of cushings
most common cause of cushing
pituitary adenoma
dexamethasone results for diff causes
pituitary adenoma - high cortisol and slightly suppressed ACTH on dexo
ectopic - wouldnt show any cortisol supression even on high dexo
adrenal adenoma and adrenal carcinoma - low ACTH
exogenous glucocorticoids - supresses ACTH and endogenous cortisol
tests
- 24hr urinary cortisol free
- dexamethasone supression
- plasma ACTH levels
- CRH stimulation test
side effects of steroid meds
depression
mental health
insomnia
psychosis
rank how common each of the causes of cushings are
pituitary adenoma
exogenous use
paraplastic
adrenal adenoma
first line diagnostic test
overnight dexomethasone
pseudo-Cushing’s syndrome
- same finsings and test results however
- In Cushing’s syndrome, the diurnal variation in cortisol is completely lost (the variation in cortisol levels over circadian cycle)
results of each cause low and high dexamethasone
Cushing’s Disease (Pituitary adenoma):
- low dose - No suppression
- high dose - Partial suppression
Exogenous Cushing’s Syndrome:
- low dose - Suppression
- high dose - Suppression
Ectopic ACTH Syndrome:
- low dose - No suppression
- high dose - No suppression
Adrenal Tumors (ACTH-independent):
- low dose - No suppression
- high dose - No suppression
other metabolic
hyperglycaemia
ketoacidosis
likely cause if a patient is on meds or has COPD
treatment for this is roids - exogenous induced cushings
very high ACTH and no suppression
ectopic tumour - small cell lung common
no suppression after low dose, suppression after high dose, relatively high ACTH
pituitary adenoma
bitemporal haematoma
skin hyperpigmentation
lack of other pituitary hormones
nelsons syndrome
