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Flashcards in Cushing's syndrome Deck (23)
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1
Q

What does Cushing’s syndrome comprise

A

a collection of signs and symptoms caused by a chronic inappropriate elevation of free circulating cortisol

2
Q

What is the most common cause of Cushing’s syndrome

A

iatrogenic from excess exogenous glucocorticoids

3
Q

What can endogenous Cushing’s syndrome be divided into

A

ACTH dependent (80%) - excess ACTH secreted from a pituitary adenoma (Cushing’s disease) or ACTH secreted from an ectopic source usually tumours, arising from neuroendocrine cells e.g. small cell lung carcinomas, pulmonary, pancreas and thymic carcinoid tumours

ACTH independent (20%) - excess cortisol secreted from a benign adrenal adenoma or excess cortisol secreted from an adrenal carcinoma

4
Q

What are some physiological causes of hypercortisolism

A
Stress 
depression or other psychiatric disorders 
chronic alcoholism 
severe obesity 
poorly controlled diabetes 
pregnancy
5
Q

What is often useful in making a diagnosis of Cushing’s syndrome

A

Older photos of the patient compared to now

6
Q

What are some symptoms are more discriminatory to Cushing’s syndrome

A

Easy bruising
proximal muscle weakness
facial plethora
reddish-purple striae on the abdomen, breast or thighs (more than 1cm wide)
weight gain with decreasing growth velocity in children

7
Q

Name some investigations that can be performed for Cushing’s syndrome

A

24 hour urinary free cortisol
Overnight dexamethasone and low-dose dexamethasone suppression tests
Late night salivary cortisol measurements

8
Q

What are some pitfalls of 24 hour urinary free cortisol

A

It is not recommended in attends with renal failure as levels may be falsely low due to reduced glomerular filtration
High fluid intake may result in false positive results

9
Q

What are some pitfalls of the dexamethasone tests

A

Assays measure total cortisol
oestrogen increase cortisol-binding protein levels and therefore increase total cortisol. therefore they need to be stopped for 6 weeks
Dexamethasone metabolism and clearance may be increased by some drugs

10
Q

Describe the circadian rhythm in Cushing’s syndrome

A

The circadian rhythm is lost

11
Q

What are some of the pitfalls of the salivary cortisol measurement

A

The circadian rhythm may also be blunted in shift-workers

cigarette smoking - tobacco contains an enzyme that metabolises cortisol

12
Q

What other tests / investigations should be done after the screening tests

A

Plasma ACTH
High dose dexamethasone suppression
Imaging - MRI
Inferior petrosal sinus sampling

13
Q

What is the most reliable test for differentiating pituitary and non-pituitary sources

A

Inferior petrosal sinus sampling

14
Q

What is the treatment of Cushing’s syndrome due to exogenous glucocorticoid therapy

A

reduce glucocorticoid dose and discontinue if possible

15
Q

What is the treatment of choice for Cushing’s disease

A

trans-sphenoidal surgery

16
Q

Patients with evidence of remission following surgery should be given what

A

hydrocortisone replacement

17
Q

Why should patients be given hydrocortisone replacement

A

Prolonged exposure to high cortisol levels has resulted in suppression of the hypothalamic -pituitary-adrenal axis

18
Q

What might be given before surgery to control hypercortisolism and stabilise the patient

A

Adrenal enzyme inhibitors

19
Q

Describe the success of complete excision of a ectopic ACTH secreting tumour

A

most result in remission

20
Q

Describe the prognosis of Cushing’s disease

A

pretty much the same as that of an age-matched population

21
Q

What is macro nodular adrenal hyperplasia characterised by

A

adrenal glands that contain multiple non pigmented nodule larger than 5mm in diameter

22
Q

What is McCune-Albright syndrome characterised by

A

cafe au last spots
polyostotic fibrous dysplasia
precocious puberty and other endocrine disorders

23
Q

What is the treatment for Cushing’s syndrome due to an adrenal adenoma

A

unilateral adrenalectomy