(See also Introduction to Congenital Kidney Tubular Disorders Introduction to Congenital Kidney Tubular Disorders The kidneys filter and cleanse the blood. They also maintain the body’s balance of water, dissolved salts ( electrolytes, such as sodium, potassium, and calcium), and nutrients in the blood... read more .)
Bartter syndrome and Gitelman syndrome are hereditary and are usually caused by a recessive gene Recessive disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more ( see Figure: Non–X-Linked (Autosomal) Recessive Disorders 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, the parents are carriers of the gene but do not have the syndrome. However, siblings of children with the disorder might have it. 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 electrolytes Overview of Electrolytes Well over half of the body's weight is made up of water. Doctors think about the body's water as being restricted to various spaces, called fluid compartments. The three main compartments are... read more sodium and chloride in the urine. The loss of sodium and chloride leads to excessive urine production and thus mild dehydration Dehydration Dehydration is a deficiency of water in the body. Vomiting, diarrhea, excessive sweating, burns, kidney failure, and use of diuretics may cause dehydration. People feel thirsty, and as dehydration... read more .
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 Hypokalemia (Low Level of Potassium in the Blood) In hypokalemia, the level of potassium in blood is too low. A low potassium level has many causes but usually results from vomiting, diarrhea, adrenal gland disorders, or use of diuretics. A... read more ) and loss of acids in the blood that causes blood pH to be alkaline (a disorder called metabolic alkalosis Alkalosis Alkalosis is excessive blood alkalinity caused by an overabundance of bicarbonate in the blood or a loss of acid from the blood (metabolic alkalosis), or by a low level of carbon dioxide in... read more ). Although the tubules are affected in both syndromes, the kidneys are otherwise unaffected and filter out waste products normally.
Viewing the Urinary Tract
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
Symptoms of Bartter Syndrome and Gitelman Syndrome
Symptoms of Bartter syndrome may appear before birth or during infancy or early childhood.
Symptoms of Gitelman syndrome may appear from late childhood to adulthood.
However, some people, particularly those who have Gitelman syndrome have no symptoms and are diagnosed only after blood tests are done for other reasons.
Children with these syndromes have symptoms that are similar to those of people who take medications called diuretics, which increase urine output and can cause chemical imbalances in the blood. However, unlike in people taking diuretics, in people with Bartter syndrome or Gitelman syndrome, symptoms cannot be ended by simply stopping a medication.
Fetuses with Bartter syndrome may grow poorly while in the womb. Some children are born prematurely and may be intellectually disabled.
Children with Bartter syndrome and sometimes those with Gitelman syndrome may have poor growth and developmental delays. The loss of magnesium, calcium, or potassium can lead to muscle weakness, cramping, spasms, or fatigue, particularly in people with Gitelman syndrome. Children with either syndrome may have excessive thirst, may produce large amounts of urine, may crave salt, and may have nausea and vomiting.
The loss of sodium and chloride leads to chronic mild dehydration. People with Bartter syndrome or Gitelman syndrome may have low blood pressure Low Blood Pressure Low blood pressure is blood pressure low enough to cause symptoms such as dizziness and fainting. Very low blood pressure can cause damage to organs, a process called shock. Various drugs and... read more (hypotension).
In addition, people with Bartter syndrome may develop kidney stones Stones in the Urinary Tract Stones (calculi) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine. Tiny stones may cause no symptoms, but larger stones... read more or a build up of calcium in the kidneys (called nephrocalcinosis) because they have large amounts of calcium in their urine. However, people with Gitelman syndrome do not develop these problems.
Diagnosis of Bartter Syndrome and Gitelman Syndrome
Measurement of electrolyte levels in the blood and urine
Doctors suspect Bartter syndrome or Gitelman syndrome in children who have characteristic symptoms or who have abnormal levels of electrolytes in their blood and urine. Sometimes the abnormal electrolyte levels are found when laboratory tests are done for other reasons.
The diagnosis of either syndrome can be suggested by finding high levels of renin and aldosterone in the blood and high levels of sodium, chloride, and potassium in the urine.
The diagnosis is confirmed through genetic testing, which is becoming more widely available.
Family members can be evaluated by a genetic specialist or kidney specialist. Most often, genetic testing is done.
Treatment of Bartter Syndrome and Gitelman Syndrome
Supplements of sodium, potassium, and magnesium
For Bartter syndrome, nonsteroidal anti-inflammatory drugs
Because the defective functions of the tubule cells in the kidneys cannot be corrected, treatment is lifelong and is aimed at correcting the hormonal, fluid, and electrolyte abnormalities. People take supplements containing the substances that are lost in the urine, such as sodium, potassium, and magnesium, and also increase their fluid intake.
Certain medications can be helpful. People with Bartter syndrome are given nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin or ibuprofen. NSAIDs are not helpful in Gitelman syndrome.
Doctors may give growth hormone to children who are very short.