Hyperaldosteronism Flashcards
What does hyperaldosteronism refer to?
High levels of aldosterone
What is Conn’s syndrome?
An adrenal adenoma that produces too much aldosterone
What is the key presenting feature of hyperaldosteronism?
Hypertension
Where is renin excreted from?
Juxtaglomerular cells in the afferent arterioles of the kidneys
What happens to renin secretions in response to low blood pressure?
Increased secretion
What happens to renin secretions in response to high blood pressure?
Decreased secretion
What does renin do?
Converts angiotensinogen to angiotensin I
Where is angiotensin I converted to angiotensin II?
The lungs
What does angiotensin-converting enzyme (ACE) DO?
Converts angiotensin I to angiotensin II
What is aldosterone?
A mineralocorticoid steroid hormone
What does aldosterone act on?
Nephrons in the kidneys
What are the three functions of aldosterone?
Increases sodium reabsorption from the distal tubule
Increases potassium secretion from the distal tubule
Increases hydrogen secretion from the collecting ducts
What is primary hyperaldosteronism?
When the adrenal glands are directly responsible for producing too much aldosterone
Why is serum renin low in primary hyperaldosteronism?
High blood pressure suppresses it
Give three reasons the adrenals may produce too much aldosterone?
Bilateral adrenal hyperplasia (most common)
Adrenal adenoma - Conn’s syndrome
Familial hyperaldosteronism (rare)
What is secondary hyperaldosteronism?
Excessive renin stimulating the release of excessive aldosterone
Why is excessive renin released in secondary hyperaldosteronism?
Due to disproportionately lower blood pressure in the kidneys
Give three reasons for disproportionately low blood pressure in the kidneys occurring in secondary hyperaldosteronism?
Renal artery stenosis
Heart failure
Liver cirrhosis and ascites
What is renal artery stenosis?
Narrowing of the artery supplying the kidney usually due to atherosclerosis
What tests can be used to confirm renal artery stenosis?
Doppler ultrasound
CT angiogram
Magnetic resonance angiography (MRA)
What screening test is used in the investigations of hyperaldosteronism?
Aldosterone-to-renin ratio
High aldosterone and low renin indicate what on an aldosterone-to-renin ratio?
Primary hyperaldosteronism
High aldosterone and high renin indicate what on an aldosterone-to-renin ratio?
Secondary hyperaldosteronism
Which scans can be used to investigate the underlying cause of hyperaldosteronism?
CT
MRI
