Endocrine_CCT (1) Flashcards
What is the other name for hyperaldosteronism?
Hyperaldosteronism - aka Conn’s Syndrome
What happens in Conn’s syndrome?
Hyperaldosteronism (Conn’s)
- Excess production of aldosterone (independent of the renin-angiotensin system) -> an increase in the sodium and water retention
- decrease in the renin release (as compensatory mechanism)
What condition would you suspect in a patient who presents with the following:
- Hypertension
- Hypokalaemia
- Alkalosis
Serum sodium mildly raised or normal
Conn’s syndrome/ hyperaldosteronism
Symptoms of Conn’s
Symptoms of Conn’s:
- often asymptomatic
- signs of hypokalaemia
- weakness
- cramps
- paraesthesia
- polyuria
- polydipsia
- high blood pressure, sometimes but not always
Common causes of Conn’s syndrome
Common causes:
- 2/3 are due to a solitary aldosterone-producing adenoma, and that is linked to mutation in K+ channels
- the rest are due to bilateral adrenocortical hyperplasia
Rare causes of Conn’s syndrome
Rare causes:
- Adrenal carcinoma
- Glucocorticoid-remediable aldosteronism -the ACTH regulatory element of the 11B-hydroxylase gene fuses to the aldosterone synthase gene. This is a genetic condition which should be offered genetic testing.
- Increase aldosterone production and bringing it under the control of ACTH
Investigations in Conn’s
- U&E
- Renin
- Aldosterone
- Adrenal vein sampling
Do not rely on low potassium, and in more than 20% of the patients they are normokalaemic
Treatment for Primary hyperaldosteronism/ Conn’s (depending on cause)
- Conn’s: laparoscopic adrenalectomy
- Spironolactone for 4 weeks pre-op and that is to control BP and K+
- Hyperplasia: treated medically, spironolactone or amiloride
- Adrenal carcinoma: surgery and post operative adrenolytic therapy with mitotance (anti-neoplastic agent) -the prognosis is usually is poor
What happens in Cushing’s syndrome?
Cushing’s syndrome - clinical state where there is a chronic glucocorticoid excess + loss of the normal feedback mechanisms of they hypothalamo-pituitary-adrenal axis and the loss of the circadian rhythm of cortisol secretion
What’s Cushing’s disease?
Pituitary adenoma causing an increase in ACTH
What are the commonest causes of Cushing’s syndrome?
- oral steroids -> the most common
- endogenous causes are rare -> more than 80% are due to an increase of ACTH, of these a pituitary adenoma (Cushing’s disease) is the commonest cause
What conditions may cause ectopic ACTH production?
Ectopic ACTH production: this is due to small cell lung cancer and carcinoid tumours
What happens in Dexamethasone test, when there is an ectopic release of ACTH?
Dexamethasone in high doses fails to supress the cortisol production
What happens in Dexamethasone test in case of pituitary adenoma?
Pituitary adenoma = Cushing’s disease
- low-dose dexamethasone test leads to no change in the plasma cortisol
- 8mg may be enough to halve the morning cortisol
What happens on Dexamethasone test in case of adrenal adenoma?
Adrenal adenoma/cancer: because thetumour is autonomous dextamethasone in any dose will not supress the cotisol