Adrenal Disease Flashcards
Explain the anatomy of the adrenal gland and the function of each later
Adrenal cortex: Granulosa which produces aldosterone. Fasciculata which produces cortisol. Reticularis which produces androgens.
Adrenal medulla: Chromograffin cells which produces catecholamine
What is the function of aldosterone?
It binds to the mineralocorticoid receptor which activates the sodium channel to reabsorb sodium and water.
Explain the regulation of cortisol release?
Negative feedback from cortisol to the hypothalamus regulates the amount of corticotropin releasing hormone send to the anterior pituitary which regulates the amount of ACTH released
What are the clinical features of Cushing’s disease?
- Moon faces,
- Buffalo hump,
- Psychiatric symptoms,
- Thin arms and legs
- Thinning of the skin,
- Hirsutism,
- Increased abdominal fat and striae,
- Osteoporosis,
- Bruising,
- Poor wound healing and susceptibility for infection
What are the investigations for Cushing’s syndrome?
Two of the following:
- 24h urine free cortisol,
- 3 spot tests of Urine cortisol to creatinine ratio.
- Dexamethasone suppression test
- Late night salivary cortisol
Explain the dexamethasone suppression test
- It is either done overnight (high dose) or a low dose test over 48 hours. Plasma cortisol should be undetectable in normal circumstances as the large dose of dexamethasone should suppress normal cortisol production. If a Pituitary pathology then cortisol will be suppressed to below 50%
What are the causes of Cushings syndrome?
- ACTH dependent eg, pituitary adenoma, ectopic ACTH or ectopic CRH.
- ACTH independent eg, Adrenal adenoma, adrenal carcinoma or nodular hyperplasia (suggests adrenal pathology)
What are some causes of adrenal insufficiency and its symptoms
- Addison’s disease (autoimmune destruction)
- It presents with anorexia, weight loss, fatigue, dizziness and low BP, abdominal pain, vomiting and diarrhoea and skin pigmentation (specifically on palmar creases and buccal mucosa)
What are the investigations for adrenal insufficiency?
- UEs (low sodium, high potassium and hypoglycaemia),
- Short Synacthen test ( measure plasma cortisol before ATCH injection and after, cortisol should have risen but in adrenal insufficiency it won’t have)
- Investigate normal ACTH levels (which should be high due to the lack of cortisol, this causes the skin pigmentation)
- Renin/aldosterone levels. Renin is high and aldosterone is low.
- Adrenal autoantibodies
What is congenital adrenal hyperplasia?
Autosomal recessive defect in steroidgenic genes. Eg, 21 alpha hydroxylase deficiency which prevents the formation of aldosterone and cortisol.
What is the presentation and treatment of congenital adrenal hyperplasia?
Females - ambiguous genitalia.
Males - Adrenal crisis (hyponatraemia and hypotention) and early virilisation. The presentation is due to the lack of cortisol/aldosterone stimulating production of more ATCH but as it cannot produce cortisol/aldosterone then it results in excess adrenal androgens.
- Treated with mineralocorticoid and glucocorticoid
What is the presentation of late onset congenital adrenal hyperplasia and its causes
- This is caused by a partial 21 alpha hydroxylase deficiency. While there is normal cortisol, there is increased ACTH which causes increased adrenal androgens. This leads to oligomenorrhoea, hirsutism and reduced fertility.
- Diagnosis via synacthen test
What results indicate primary aldosteronism (Conns/hyperaldosteroneism)
- Suspicious when resistant hypertension, hypokalaemic and metabolic acidosis
- Presents with high aldosterone, low renin and a aldosterone to renin ration over 35. The ARR is the best screening tool
What are the confirmatory tests for primary aldosteronism
- Try to stop medications, especially beta blockers and mineralocorticoid antagonists (to get a true reflection of the normal aldosterone levels) Can use alternatives like verapamil.
- Then to a saline suppression test - 2L of saline over 4H. At 4h measure the aldosterone. If over 270 then suspicious and should do imaging.
Explain the management of primary hyperaldosteronism
- If adrenal adenoma then do unilateral laproscopic adrenalectomy. This can cure hyperkalaemia and hypertension.
- Or give R antagonism eg, spironolactone or eplerenone
What is a paraganglioma?
Extra adrenal neural crest cell tumour. Produces similar symptoms to a phaeochromocytoma
What are the signs and symptoms of a phaeochromocytoma
- Hypertension (intermitant in 50%)
- Episodes of headaches, palpitations, palor, sweating, tremor, anxiety, nausea, vomiting, chest or abdo pain.
- Usually a 15 min crisis
- Investigate via CT and MIBG
What are some of the genetic conditions associated with phaeochromocytoma
- Multiple endocrine neoplasia (MEN)
- VHL,
-SDHB and SDHD mutations, - Nerofibromatosis.
What is the treatment of a phaeochromocytoma?
- Alpha blockade via doxazosin and aim for SBP under 120mmHg.
- Then beta blocker if tachycardic but only given once patient is fully alpha blocked or it can induce a crisis
- Encourage salt intake,
- Surgical removal
Describe features of an incidentaloma
- Incidentally discovered adrenal lesion which can be malignant or functional.
- More likely to be malignant if over 4cm and more dense. Can a dynamic scan
- If functional, can release any adrenal hormone
What is the function of cortisol?
- Increases BP,
- Inhibits bone formation,
- Increases insulin resistance,
- Inhibits inflammatory/immune responses,
- Maintains function of skeletal and cardiac muscles.
