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What

In Bartter syndrome, there is a defect in the way the kidneys work. Usually the kidneys filter the blood and make sure that the right levels of electrolytes are present in the blood, which is important for the normal functioning of the body. The electrolytes in the blood include sodium, potassium, and chloride. Since the kidneys don’t work correctly in this syndrome, it leads to alkaline blood that has low amounts of potassium and chloride. This leads to poor growth, fatigue, and muscle weakness, and in some cases, kidney failure. Early diagnosis and treatment can help improve growth and prevent more severe complications. There are four different types of Bartter syndrome, all of which are similar, but with a few differences.

Who

The exact incidence of Bartter syndrome is not known, but estimated to be about 1 in a million live births in the US. The incidence varies in other countries. Bartter syndrome occurs in males and females, and in all ethnicities. Both sporadic and familial (inherited) cases of Bartter syndrome have been reported. Some of the familial cases show that Bartter syndrome may be an autosomal recessive type of genetic disorder. This means that the parents both have an altered gene causing the syndrome and that the affected child inherited two altered copies, one from each parent. The parents aren’t affected since they have one normal copy of the gene, in addition to the altered copy.

Signs and Symptoms

Children with Bartter syndrome may have many or few of the following signs and symptoms. These symptoms will often be present at birth, though depending on the type they may appear any time in childhood.

• Slow, delayed growth: the child may have difficulties growing in height and gaining an appropriate amount of weight
• Fatigue and generalized weakness
  
• Muscle weakness
  
• Tetany: which means that the muscles may twitch, spasm, or cramp. In severe cases, there may be seizures.
  
• Increased frequency of urination and increased thirst
  
• Frequent vomiting
  
• Kidney stones
  
• Developmental delays: the child may have difficulties reaching motor and verbal milestones
  
• In type four, there is associated hearing loss.

Possible Causes

In Bartter syndrome, individuals usually have defects in genes that are important for the normal functioning of the kidneys. Different genes cause the different types of Bartter syndrome, but because they all affect the same part of the kidney, the appearance of the disease is very similar. These genes normally help form certain proteins that help filter the blood and maintain the correct levels of electrolytes in the blood. In many cases, the gene defects initially cause a loss of sodium, potassium, chloride in the urine, leading to dehydration. This leads to increased concentrations of certain chemical messengers (aldosterone and prostaglandins) and sets up a cycle of constant potassium and chloride loss from the blood into the urine, and makes the blood more alkaline then normal. Treatment for Bartter syndrome tries to maintain the normal amount of electrolytes in the blood.

Diagnosis

Bartter syndrome is diagnosed based on the clinical features it causes, and based on the results from blood and urine tests. The blood and urine tests may show the following results. Blood tests: • Hypokalemia: low potassium levels in the blood • Hypochloremia: low chloride levels in the blood • Metabolic alkalosis: the blood is more alkaline then normal • High levels of renin, aldosterone, angiotensin II in the blood Urine Tests: • High levels of excreted potassium in the urine (which is sometimes called potassium wasting) • High levels of excreted chloride • Normal to high levels of calcium and usually normal levels of magnesium • High levels of prostaglandin E2 in the urine Individuals with Bartter syndrome usually have a low to normal blood pressure. In a few cases, a biopsy of kidney tissue may be done and show that certain cells (called the JGA cells), have become enlarged. Since abnormal levels of electrolytes in the blood can affect the way that the heart and other muscles function, an EKG may be done to check how the heart is functioning.

Treatment

The main goal of the treatment will be to try to maintain the correct levels of electrolytes in the blood (especially potassium), since these electrolytes are so important for the normal functioning of the body. The treatment consists of a potassium-rich diet (foods like bananas and raisins) and supplements of potassium and chloride. To try to reduce the amount of potassium and chloride that is lost in the urine, doctors may recommend different types of medications. These include certain diuretics that increase potassium, and medications that reduce the effect of the aldosterone and prostaglandins. It is also important to prevent getting dehydrated, which can exacerbate the signs and symptoms of Bartter syndrome. Regular blood and urine exams are recommended with follow-ups with a nephrologist (kidney specialist).

Prognosis

Children with Bartter syndrome will grow better and should do well if they are treated and take the supplemental potassium and other medications that they need. The medications used to treat the disease (indomethacin) can cause ulcers, so children should be monitored for this. Despite adequate treatment, some children may develop some degree of kidney failure over time, but most do not appear to do so.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

The Bartter Site
This is a great website that provides a parent-friendly summary on Bartter syndrome and provides a support group and discussion forum for families. They also provide other resources, such as recipes, articles on this syndrome, and links to other websites.

The Gaps Index
These websites provide summarized, general information on Bartter syndrome.

Medline Plus
An easy to read article on Bartter Syndrome with definitions of medical terms.

Google Search for Bartter syndrome

References and Sources

The Bartter Site www.barttersite.org This is a great website that provides a parent-friendly summary on Bartter syndrome and provides a support group and discussion forum for families. They also provide other resources, such as recipes, articles on this syndrome, and links to other websites. All Refer Health health.allrefer.com/health/bartters-syndrome-info.html This website is focused to health items, diseases and conditions with a brief general overview of a multitude of topics. There are links to other topics and health issues. The Gaps Index www.icomm.ca/geneinfo/bartters.htm These websites provide summarized, general information on Bartter syndrome.