Liddle's syndrome
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| OMIM | 177200 |
|---|---|
| DiseasesDB | 7471 |
Liddle's Syndrome is an autosomal dominant disorder that mimics hyperaldosteronism.
It involves problems with excess absorption of sodium and loss of potassium.
The syndrome is independent of aldosterone levels which are usually low. Despite its independence of aldosterone levels, it is commonly mistaken in the clinics as primary or secondary hyperaldosteronism. This critical error can be prevented by simple differential diagnoses. The first test that should be done is to measure the level of aldosterone secretion, if rates are low you can rule out hyperaldosteronism. There is both primary and secondary hyperaldosteronism. Primary a.k.a Conn's syndrome, is due to an aldosterone secreting tumor. Secondary hyperaldosteronism is due to a number of causes including renal artery stenosis, chronic renal failure, congestive heart failure (CHF), cirrhosis, or nephrotic syndrome. The second step in your differential should be to administer an aldosterone antagonist while monitoring the patients blood pressure and serum potassium (K+ monitoring should be standard due to aldosterones propensity to cause hypokalemia). Spironolactone is often used because of its mineralcorticoid receptor antagonistic properties.
The syndrome is caused by disregulation of an epithelial Na+ channel (ENaC) due to a genetic mutation. The mutation changes a domain in the channel so it is no longer degraded correctly by the Ubiquitin Proteasome system. Specifically the PY motif in the protein is deleted or altered so the E3 ligase (Nedd4) no longer recognizes the channel.
The treatment is with a potassium sparing diuretic such as amiloride or triamterene.This both normalizes blood pressure and serum potassium.
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