what is Addison’s disease?
primary adrenal insufficiency
there is a total or near-total destruction of the adrenal cortex, causing a deficiency in cortisol and aldosterone
what are the causes of Addison’s disease?
- autoimmune destruction of adrenal glands
- infective - TB/CMV
- adrenal haemorrhage
- bilateral adrenal infarction
- adrenal metastases
- removal of adrenal glands in surgery
- genetic (congenital adrenal hypoplasia)
what is the presentation of Addison’s disease?
- fatigue
- weight loss
- muscle weakness
- decreased appetite
- salt craving
- abdominal pain
- nausea and vomiting
- postural hypotension
- hyper pigmentation
what investigations are carried out when suspecting Addison’s disease?
- U&E (hyponatraemia, hyperkalaemia) (due to low aldosterone)
- ABG - metabolic acidosis
- Blood glucose - hypoglycaemia (due to low cortisol)
- 9 am serum cortisol (low)
- plasma aldosterone concentration (low)
- Short Synacthen test (synthetic ACTH given - cortisol levels fail to rise as much as they should)
- endogenous ACTH levels (High - Addison’s (-ve feedback), low - 2ry adrenal insufficiency (decreased ACTH causes decreased cortisol))
- anti adrenal antibodies
how is Addison’s disease managed?
- cortisol replacement with hydrocortisone (10mg on waking, 5mg at midday, 5mg in early evening)
- aldosterone replacement with fludrocortisone
what is an Addison/adrenal crisis?
life-threatening cortisol deficiency, occurring due to a precipitating event, such as infection or burns.
how do patients in Addisonian crisis present?
- shock, often refractory to IV fluid resuscitation
- nausea and vomiting
- abdominal pain
- malaise
- muscle pains and cramps
- often known Addison’s disease or on steroid medication
how would you investigate a patient with suspected addisonian crisis?
- bloods for cortisol and ACTH (straight to lab - call ahead)
- U&Es - hyperkalaemia and hyponatraemia (keep monitoring)
- blood glucose (low - keep monitoring)
- blood urine, sputum and urine culture then antibiotics if concerned about infection
what is the initial management of a patient with suspected addisonian crisis?
- IV hydrocortisone - 100 mg
- rehydration with 0.9% saline (500 mL boluses and repeated as necessary to maintain BP)
- careful monitoring of BP, fluid status and serum sodium and potassium
- calcium glutinate if ECG changes due to hyperkalaemia
what is the treatment of addisonian crisis once the patient has been stabilised?
- IV fluids (guided by fluid status and U&Es)
- continue hydrocortisone (100mg/8hours IV or IM)
- change to oral steroid after 72 hours if stable (hydrocortisone)
- fludrocortisone
(hydrocortisone and fludrocortisone for life) - normal saline and dextrose (to replace glucose) (careful not to worsen hyponatraemia)
what is secondary adrenal insufficiency?
low cortisol due to low ACTH levels
what are the causes of secondary adrenal insufficiency?
- sudden withdrawal of steroids in someone who is taking them long-term
- surgical removal of benign ACTH-secreting tumours (Cushing’s disease)
- hypopituitarism (due to infection, ischaemia or trauma)
what is Conn’s syndrome?
primary hyperaldosteronism
what are the causes of Conn’s syndrome?
- unilateral benign adrenal adenoma
- bilateral adrenal hyperplasia
what is the presentation of Conn’s syndrome?
suspect in anyone who is:
- hypertensive
- hypokalaemic
- alkalotic
- headaches
- retinopathy
- weakness
- palpitations
describe the pathophysiology of Conn’s syndrome
High levels of aldosterone cause increased expression of NaK ATPase in DCT and CD. causes increased Na reabsorption and therefore increased water reabsorption - hypertension.
This also causes increased levels of potassium excretion, leading to hypokalaemia and alkalosis (reciprocal cation shifts).
what are the investigations that are carried out when suspecting Conn’s syndrome?
- U&Es (hypokalemaia, hypernatraemia)
- Aldosterone:renin ratio (raised)
- imaging - CT of adrenal glands
- ECG (to check for changed due to hypokalaemia)
how would you manage Conn’s syndrome?
- unilateral adrenal adenoma is removed via laparoscopic adrenalectomy
- bilateral disease is treated with medication (spironolactone (aldosterone antagonist) and possibly antihypertensives
what is a pheochromocytoma?
tumour of the adrenal medulla causing excessive secretion of catecholamines
most are benign
what is the presentation of pheochromocytoma?
may bee asymptomatic
- anxiety
- headache
- palpitations
- sweating
- hypertension
- tachycardia
- pallor
what investigations are carried out when suspecting a pheochromocytoma?
- biochemical testing of urine (24 hour urine collection) (testing for catecholamines and their breakdown products-metadrenaline and normetadrenaline)
- plasma metadrenaline and normetadrenaline levels (bfeakdown products of adrenaline and noradrenaline)
- imaging - CT abdomen (looking for tumour of adrenal gland)
what is the management of pheochromocytoma?
- alpha blockers (doxazosin) - prevents vasoconstriction and therefore lowers BP
- beta blockers (bisoprolol) - lowers heart rate
- always alpha block before beta block*
- surgical removal of the tumour
what are the complications of undiagnosed pheochromocytomas?
- hypertensive crisis
- stroke
- cardiac complications
