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Adrenal Disorders (Cushing's Disease (Functions of cortisol (Sodium…
Adrenal Disorders
Cushing's Disease
Cushing's Disease = Refers to Cushing's syndrome caused by a pituitary adenoma secreting inappropriate ACTH
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Cushing's Syndrome = Clinical state produced by excessive cortisol, loss of the hypothalamic pituitary axis feedback and loss of circadian rhythm. Chief cause is oral steroids
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Signs
Catracts
Ulcers
Skin - striae
Hyperglycaemia, hypertension
Increased infection
Necrosis
Glucosuria
^CUSHING
Clinical Presentation
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Mood change - depression, lethargy, psychosis
Investigations
Do not do random cortisol test as cortisol levels change with stress, time of day and illness
Dexamethasone suppression test: dexamethasone suppresses cortisol levels. A failure to suppress over a 24 hour period is diagnostic of Cushing's
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Treatment
Adrenalectomy - this will cause ACTH levels to build up as no cortisol is produced so there is no negative feedback. Causes jaundice
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Hyperaldosteronism
Primary = Excess production of aldosterone, independent of the renin-angiotensin-aldosterone system
Secondary = High aldosterone due to high renin caused by low renal perfusion e.g. in renal artery stenosis, hypertension, diuretics, hepatic failure, congestive heart failure
Pathogenesis
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Excess aldosterone increases sodium, causing water retention which leads to hypertension and decreased renin release
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Epidemiology
Rare, accounts for <1% of all hypertension
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Investigations
U&E analysis: will show decreased renin, increased aldosterone
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ECG: flat T, long PR, long QT, ST depression, U wave
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Addison's Disease
= Destruction of entire adrenal cortex resulting in aldosterone, cortisol and androgen deficiency. Autoimmune
Epidemiology
Very rare: 0.8 in 100,000
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Symptoms
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Tearful, depression, low mood
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Investigations
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ACTH stimulation test. Measure plasma cortisol before and 30 mins after IM tetracosactide (ACTH analogue). A cortisol level >550 nmol/L means it's not Addisons
Eosinophilia, as a reduction in cortisol will cause raised white cells
If there is TB history, do a chest x-ray to look for fibrosis
Treatment
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Do not abruptly stop steroids. Give patient steroid drug card and bracelet. Double steroid dose in infection, trauma, surgery. Increase dose in pregnancy and before exercise to mimic normal body response.
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Secondary Hypoadrenalism
There is reduced release of ACTH, resulting in reduced cortisol but maintained mineralocorticoid production.
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Not an issue with adrenal glands, but pituitary
Adrenal Glands
Structure
Cortex
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Zona Glomerulosa: Mineralocorticoids e.g. Aldosterone. Zona glomerulosa is NOT under control of hypothalamo-pituitary axis, it is under control of renin release from juxtaglomerular cells in kidney
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