Adrenal Disease Flashcards
What is the function of aldosterone?
Acts on the mineralocorticoid receptors on the distal tubule and collecting duct causing sodium retention and potassium excretion
What is Cushing’s syndrome and what are the causes of it ?
A clinical state produced by chronic glucocorticoid excess from any cause
Causes:
Oral steroids
Endogenous causes
ACTH dependent: conditions that have high ACTH levels (Cushing’s disease, ectopic ACTH production)
ACTH independent: excessive cortisol secretion by adrenal glands despite a suppressed ACTH level (adrenal adenomas, bilateral adrenal hyperplasia)
What is Cushing’s disease?
A pituitary tumour secreting ACTH
What is the management of Cushing’s disease?
1) Mifepristone (glucocorticoid receptor antagonist) 300mg PO once daily before surgery
2) Transphenoidal pituitary adenectomy
3) Post surgery: hydrocortisone 10-25mg PO in 2-3 divided dose
What can often mimick Cushing’s disease?
Alcohol excess
What is Addison’s disease?
Destruction of the adrenal cortex causing cortisol and aldosterone deficiency. 80% due to autoimmunity
Name some causes of Addison’s disease
Autoimmunity
Adrenal metastases from breast, lung and renal cancer
Tuberculosis
Lymphoma
Secondary: exogenous steroids (suppresses the HPA axis)
What are symptoms of Addison’s disease?
Lean, tanned, pigmented palmar creases and buccal mucosa, tired, tearful
Anorexia, unexplained vomiting and abdominal pain
Depression, psychosis
What are the investigations of Addison’s disease and what will they show?
Serum electrolytes: low sodium, high potassium
Urea may be elevated
9am serum cortisol (100-500 should prompt a short synacthen test)
Short synacthen test: gold standard, plasma cortisol measured before and after 30mins after giving synacthen 30mg IM
What is the management of Addison’s disease
Hydrocortisone 20-30mg per day in 2-3 divided doses
Fludracortisone
If ill, the glucocorticoid dose should be doubled
What happens in an Addisonian crisis?
Severe adrenal insufficiency
Causes:
Sepsis or surgery causing an acute exacerbation
Adrenal haemorrhage (Waterhouse-Friedrich syndrome)
Steroid withdrawal
What is the management of an Addisonian crisis?
Hydrocortisone 100mg IM or IV
IL normal saline over 30-60 minutes
What is a pheochromocytoma?
Tumour of the adrenal medulla, originates in the chromaffin cells. Secretes catecholamines (adrenaline and noradrenaline).
Symptoms: triad: episodic headache, tachycardia, sweating. Also get palpitations and anxiety
What are the investigations and treatment of a pheochromocytoma?
Investigations: 24 hour urinary collection to measure metanephrines, abdominal CT/MRI
Treatment: alpha blocker (phenoxybenzamine) and beta blocker (propranolol)
What are the primary causes of hyperaldosteronism?
Idiopathic: zona glomerulosa has an increased number of aldosterone secreting cells
Conn’s syndrome: adenoma secreting aldosterone
Familial hyperaldosteronism (genetic)
What are the secondary causes of hyperaldosteronism?
Chronic low blood pressure (congestive heart failure, or cirrhosis)
Leads to increased levels of renin
Leads to excess aldosterone production
What are the investigations of hyperaldosteronism and what do they show?
1) Aldosterone/renin ratio
2) High resolution CT abdomen following 1)
Electrolytes: hypokalaemia, hypernatraemia
The increased sodium in blood leads to hypertension
Metabolic alkalosis will also occur
Headaches and facial flushing will be seen due to hypernatraemia
Constipation and arrythmias will be seen due to hypokalaemia
How do you diagnose primary hyperaldosteronism?
Will show low renin and high aldosterone due to the negative feedback effect
How do you diagnose secondary hyperaldosteronism?
High renin and aldosteronism
How do you treat hyperaldosteronism?
Potassium sparing diuretics (spironolactone) in particular
Treat underlying cause (e.g. excision of tumour in Conn’s)
What occurs in congenital adrenal hyperplasia?
A group of autosomal recessive conditions that affect adrenal steroid synthesis. Low resultant cortisol leads to excess ACTH production by the pituitary, and this stimulates adrenal androgens.
What is the main cause of congenital adrenal hyperplasia and what are the features of it?
21-hydroxylase deficiency (90%)
Virilisation in females
Precocious puberty in males 60-70% patients will have a salt losing crisis at 1-3 weeks
