Bartter syndrome and gitelman syndrome

[Zipporah Schumaker]

In Bartter syndrome and Gitelman syndrome, a hereditary defect of the kidney tubules causes the kidneys to excrete excessive amounts of electrolytes (potassium, sodium, and chloride), resulting in growth, electrolyte, and sometimes nerve and muscle abnormalities.
(See also Introduction to Congenital Kidney Tubular Disorders.)
Bartter syndrome and Gitelman syndrome are hereditary and are usually caused by a recessive gene (see Figure: Non–X-Linked (Autosomal) Recessive Disorders). Thus, a person with Bartter syndrome or Gitelman syndrome has usually inherited two recessive genes for the disorder, one from each parent. Because two genes are needed when a recessive gene is involved, there are usually no other immediate family members with the syndrome. Although both are rare, Gitelman syndrome is more common than Bartter syndrome.
In Bartter syndrome and Gitelman syndrome, the kidneys cannot reabsorb salt (sodium chloride) normally from the kidney tubule. Thus, the kidneys excrete excessive amounts of the electrolytessodium and chloride in the urine. The loss of sodium and chloride leads to excessive urine production and thus mild dehydration.
Mild dehydration causes the body to produce more of the enzyme renin and the hormone aldosterone, which help regulate blood pressure. The increase in aldosterone increases potassium and acid secretion in the kidneys, leading to low blood potassium (hypokalemia) and loss of acids in the blood that causes blood pH to be alkaline (a disorder called metabolic alkalosis). Although the tubules are affected in both syndromes, the kidneys are otherwise unaffected and filter out waste products normally.
The main differences between the two syndromes are

The genes that are involved
The part of the tubule that is affected
The age at which symptoms begin

[Lanell]

Bartter syndrome and Gitelman syndrome are autosomal recessive renal disorders characterized by fluid, electrolyte, urinary, and hormonal abnormalities, including renal potassium, sodium, chloride, and hydrogen wasting; hypokalemia; hyperreninemia and hyperaldosteronism without hypertension; and metabolic alkalosis. Findings include electrolyte, growth, and sometimes neuromuscular abnormalities. Diagnosis is assisted by urine electrolyte measurements and hormone assays but is typically a diagnosis of exclusion. Treatment consists of nonsteroidal anti-inflammatory drugs, potassium-sparing diuretics, low-dose angiotensin-converting enzyme inhibitors, and electrolyte replacement.