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Flashcards in Endocrine Deck (16):

What is the difference between Cushing's disease and Cushing's syndrome?

Syndrome is a group of symptoms due to high cortisol
Disease is a specific pathology caused by pituitary adenoma


What is the normal cortisol axis?

Hypothalamus secretes CRH stimulating pituitary to produce ACTH stimulating the adrenal cortex to produce cortisol


What are the 5 main effects of cortisol in the body?

Increase gluconeogenesis
Increase lipolysis
Increase proteolysis
Increase sensitivity of blood vessels to catecholamines
Decrease immune response


What are the two types of corticosteroids and what does this mean?

Steroids produced by the adrenal cortex
Mineralcorticoids (aldosterone)
Glucocorticoids (cortisol)


Where are mineralcorticoids produced?

Zona glomerulosa


Where are glucocorticoids produced?

Zona fasicularis


What is a phaemochromacytoma and the key symptoms?

Tumour of the medulla of the adrenal glands causing excess secretion of catecholamines
Headache, palpitations, sweating, hypertension


What are the 5 main problems arising from excess cortisol?

Muscle, bone and skin breakdown
Hyperglycemia, insulin resistance and diabetes
Central obesity, moon face, buffalo hump
Increased infection risk


What is Addisons?

Primary adrenal insufficiency
Adrenals produce low cortisol most commonly due to AI destruction or TB


Test for Cushings syndrome?

Low dose dexamethasone test (1mg)
Positive if cortisol not suppressed and remains >50


What are the three main causes of endogenous Cushing's and features of each?

Pituitary adenoma (Cushing's Disease, ACTH high, CRH low)
Ectopic ACTH (Small cell lung Ca, ACTH very high, CRH low)
Adrenal tumours (ACTH low, CRH low)


How do you distinguish between Cushing's disease and ectopic ACTH production?

High dose dexamethasone test (8mg)


Where are catecholamines mainly produced?

Medulla of adrenals
Post ganglionic sympathetic neurones


What is Conns disease?

Adenoma of the adrenal glands causing primary hyperaldesterism


What does aldosterone do?

Increase Na+ re-absorption by affecting Na/K pump on DCT
Increases H+ excretion in urine and HCO3- into blood


Summary of the RAAS?

Low kidney perfusion detected by juxtoglomerullar aparatus causes secretion of renin into the blood. Renin converts angiotensinogen into angiotensin 1. ACE converts 1 to 2. Angiotensin 2 vasoconstricts and increases aldosterone production by the adrenal medulla. Aldosterone increases Na reaspsorption.