Liddle's Syndrome

Definition

Definition of Liddle's Syndrome
Liddle's syndrome, also called Liddle syndrome and pseudoaldosteronism, is an autosomal dominant disorder characterized by early, and frequently severe, hypertension associated with low plasma renin activity, metabolic alkalosis due to hypokalemia, and hypoaldosteronism (low secretion of aldosterone). Liddle syndrome involves abnormal kidney function, with excess reabsorption of sodium and loss of potassium from the renal tubule, and is treated with a combination of low sodium diet and potassium-sparing diuretic drugs (e.g., amiloride). It is extremely rare, with fewer than 30 pedigrees or isolated cases having been reported worldwide as of 2008.

Symptoms

Symptoms of Liddle's Syndrome
Children with Liddle syndrome are frequently asymptomatic. The first indication of the syndrome often is the incidental finding of hypertension during a routine physical exam. Because this syndrome is rare it may only be considered by the treating physician after the child's hypertension does not respond to antihypertensive agents.

Adults could present with nonspecific symptoms of hypokalemia, which can include weakness, fatigue, palpitations or muscular weakness (dyspnea, constipation/ abdominal distention or exercise intolerance). Additionally, long standing hypertension could become symptomatic.

Causes

Causes of Liddle's Syndrome
Liddle syndrome develops when the kidneys expel potassium but hold extreme amounts of water and sodium and lead to elevated blood pressure. The gene causing this syndrome is dominant, meaning that if any individual has this mutated gene, then their children have a 50% chance of receiving this defective gene.

Liddle syndrome is linked with low plasma renin action, metabolic alkalosis owing to hypokalemia and hypoaldosteronism – or low secretion of aldosterone. This is only one of numerous circumstances with this uncommon set of features known communally as pseudohyperaldosteronism. High blood pressure caused by this syndrome often starts in infancy.

Liddle syndrome contains atypical function of the kidneys, with additional resorption of sodium as well as the loss of potassium thru the renal tubule, and is frozen with blend of diet that is low in sodium and diruetic drugs that are potassium-sparing.

Diagnosis

Diagnosis of Liddle's Syndrome
Evaluation of the pediatric hypertensive patient usually involves analysis of blood electrolytes and an aldosterone level, as well as other tests. In Liddle's disease, the serum sodium is typically elevated, the serum potassium is reduced, and the serum bicarbonate is elevated. These findings are also found in hyperaldosteronism, another rare cause of pediatric hypertension. Primary hyperaldosteronism (also known as Conn's syndrome), is due to an aldosterone-secreting adrenal tumor or adrenal hyperplasia. Aldosterone levels are high in hyperaldosteronism, whereas they are low to normal in Liddle syndrome.

Treatment

Treatment of Liddle's Syndrome
The treatment is with a low sodium (low salt) diet and a potassium-sparing diuretic that directly blocks the sodium channel. Potassium-sparing diuretics that are effective for this purpose include amiloride and triamterene; spironolactone is not effective because it acts by regulating aldosterone and Liddle syndrome does not respond to this regulation.

Prevention

Prevention of Liddle's Syndrome
Treatment requires a diuretic that removes sodium but helps to maintain healthy levels of potassium in the body.