11: Cushing's syndrome, hypopituitarism and diabetes insipidus Flashcards
What hormones are produced in excess in Cushing’s syndrome?
ACTH excess causing
Cortisol, aldosterone and androgen excess
The body doesn’t have a lot of stored carbohydrate (glycogen) - what is used instead in chronic cortisol excess (e.g in Cushing’s syndrome)?
Protein - causing myopathy, osteoporosis, thinning of skin
What occurs due to hyperglycaemia in Cushing’s syndrome?
Diabetes
Why do patients with Cushing’s syndrome develop central obesity?
Rapid access fat deposits
Cushing’s syndrome also produces ___ symptoms.
psychological
What other hormones are produced in excess due to cortisol excess in Cushing’s syndrome?
Cortiosteroids - causing hypertension, oedema?
Androgen - acne, hirsuitism, virilism
What signs and symptoms of Cushing’s would allow you to differentiate it from uncomplicated obesity?
Thin skin
Proximal myopathy
Osteoporosis (obesity usually STRENGTHENS bones due to increase weight bearing; do not confuse with arthropathy)
What phrase is used to describe the appearance of a patient with Cushing’s syndrome?
Lemon on matchsticks
As Cushing’s involves excess cortisol, what test is used to diagnose it?
Dexamethasone suppression test
cortisol is a steroid - administer high dose of steroids to see if body suppresses it by negative feedback
How is a dexamethasone test done?
Overnight suppression test
If cortisol is < 50nmol/L the next morning, normal
If > 100, abnormal
As cortisol secretion has a Circadian rhythm, what other test can be done to diagnose Cushing’s?
Diurnal variation test
should vary, in Cushing’s it is constant
What is the most common cause of Cushing’s disease?
Pituitary adenoma
pituitary - “ disease
anything else - “ syndrome
What are three causes of Cushing’s syndrome?
Adrenal adenoma
Ectopic ACTH production by tumours
Alcohol, depression and steroids (false positive screening tests)
Which types of steroid medication can cause pseudo-Cushing’s syndrome?
Dexamethasone, prednisolone
Topical, INH
