Conn’s Syndrome Flashcards
What is Conn’s syndrome?
Hyper aldosteronism with metabolic ALKALOSIS and hypokalemia because of higher K+ loss and Na+ reabsorption
What is the most common cause of Conn’s?
Bilateral adrenal hyperplasia
Also cased by adrenal adenoma and familial hyper aldosteronism
What is the presentation of Conn’s?
Polyuria
Polydipsia
Lethargy
Headaches
How is Conn’s syndrome diagnosed?
Aldosterone renin ratio
High resolution CT or MRI
What is the management of Conn’s syndrome?
Using imaging
Selective adrenal venous sampling
What is Bartter’s syndrome?
An inherited cause of severe hypokalaemia due to defective chloride absorption at the Na+ K+ 2Cl- cotransporter in the ascending loop of Henle
Usually autosomal recessive and associated with normotension
What is the main feature of Bartter’s syndrome?
Severe hypokalaemia
Associated with normotension, unlike other endocrine causes of hypokalaemia
How do loop diuretics relate to Bartter’s syndrome?
They inhibit NKCC2, similar to the effects of Bartter’s syndrome
Example: large doses of furosemide
What are some common features of Bartter’s syndrome?
- Failure to thrive
- Polyuria
- Polydipsia
- Weakness
Usually presents in childhood
What is Cushing’s syndrome?
Any condition causing high cortisol
Cushing’s disease specifically refers to a pituitary tumor producing ACTH
What is the most common cause of ACTH-dependent Cushing’s syndrome?
Cushing’s disease (pituitary tumor secreting ACTH)
Accounts for 80% of cases
What is an example of ectopic ACTH production?
Small cell lung cancer
Accounts for 5-10% of ACTH-dependent causes
Name two ACTH-independent causes of Cushing’s syndrome.
- Iatrogenic (steroids)
- Adrenal adenoma
Adrenal carcinoma and Carney complex are also causes
What is pseudo-Cushing’s?
Conditions that mimic Cushing’s syndrome
Often due to alcohol excess or severe depression
What metabolic condition may be seen in Cushing’s syndrome?
Hypokalaemic metabolic alkalosis
May also include impaired glucose tolerance
What are the three most commonly used tests to confirm Cushing’s syndrome?
- Overnight (low-dose) dexamethasone suppression test
- 24 hr urinary free cortisol
- Bedtime salivary cortisol
Dexamethasone test is the most sensitive and used first-line
What does a suppressed ACTH level indicate in the context of Cushing’s syndrome?
A likely non-ACTH dependent cause, such as an adrenal adenoma
First-line localisation test includes 9am and midnight plasma ACTH and cortisol levels
In the dexamethasone suppression test, what indicates Cushing’s disease?
Both cortisol and ACTH are suppressed
If cortisol is not suppressed and ACTH is, it suggests adrenal adenoma
What does a high-dose dexamethasone suppression test reveal for ectopic ACTH?
If cortisol and ACTH are not suppressed, it indicates ectopic ACTH syndrome
Differentiates between sources of ACTH secretion
What is the purpose of CRH stimulation test?
To differentiate between pituitary and ectopic/adrenal sources of ACTH
If cortisol rises, it indicates a pituitary source
What is Bartter’s syndrome?
An inherited cause of severe hypokalaemia due to defective chloride absorption at the Na+ K+ 2Cl- cotransporter in the ascending loop of Henle
Usually autosomal recessive and associated with normotension
What is the main feature of Bartter’s syndrome?
Severe hypokalaemia
Associated with normotension, unlike other endocrine causes of hypokalaemia
How do loop diuretics relate to Bartter’s syndrome?
They inhibit NKCC2, similar to the effects of Bartter’s syndrome
Example: large doses of furosemide
What are some common features of Bartter’s syndrome?
- Failure to thrive
- Polyuria
- Polydipsia
- Weakness
Usually presents in childhood
