Bartter's syndrome is a congenital kidney disease. This condition is characterized by excessive loss of electrolytes in the urine and a decrease in their concentration in the blood, which upsets the balance in the body. The disease is hereditary, that is, parents can transmit abnormalities in the genetic material to their children, which can lead to the development of this disease in the future. Consider the causes, symptoms and treatment of this condition.
Description
Bartter’s syndrome is a genetically determined group of diseases related to tubulopathy, that is, diseases characterized by impaired resorption or secretory activity of the kidneys with normal or only slightly reduced glomerular filtration. A number of mutations of genes predisposing to this syndrome have been identified. Among them, three types can be distinguished:
- Type I - caused by a mutation in the gene encoding the Na-K-2Cl transporter on the ascending arm of the Henle loop.
- Type II - caused by mutation of the gene encoding the potassium channel ROMK.
- Type III - caused by a mutation of the CIC-Kb gene, which encodes a chloride channel on the ascending arm of the Henle loop.
Causes of the disease
This disease refers to the so-called recessive, which means that it manifests itself only when it is inherited by both parents.
Incorrect operation of ion transporters causes an imbalance in the body, there are too many losses of trace elements - potassium, sodium and chlorine ions. The basic acid-base balance is shifted and goes into metabolic alkalosis.
In response to the loss of ions, the body activates compensatory mechanisms, which are manifested, in particular, by an increase in the level of renin, angiotensin and aldosterone. These are substances that are secreted under normal conditions to reduce water loss in the kidneys and cause an increase in blood pressure.
Classification and symptoms of the disease
Bartter's syndrome is classified into:
- antenatal;
- classical;
- Gitelman's syndrome.
- pseudo-Bartter syndrome.
The antenatal type can be diagnosed during the period of intrauterine development. The characteristic signs of the disease are polyhydroamniosis occurring between 24 and 36 weeks of pregnancy. It leads, as a rule, to premature birth. Due to prematurity, such babies are underweight, they have constant drowsiness and poor appetite. If adequate treatment is not started, they can die within a few days due to dehydration and electrolyte disturbances in the body. According to the results of laboratory tests, in the first week of a child's life, metabolic alkalosis with hypokalemia can be observed. Urine - with a low specific gravity and a large amount of Na +, Cl-, Ca + and K +. Hypercalciuria can cause nephrocalcinosis. Characteristic external signs of such children are observed:
- protruding forehead;
- big eyes;
- protruding ears;
- lowered corners of the mouth;
- sometimes squint.
The classic type of syndrome is manifested by stunted growth and development in early childhood. It is characterized by the appearance of polyuria, polydipsia, vomiting, constipation, a tendency to dehydration and hypokalemic metabolic alkalosis. According to the results of laboratory tests, the Ca2 + values in the urine are within the normal range or slightly exceed the normal values. Nephrocalcinosis does not develop.
Gitelman's syndrome has similar symptoms with the classic Bartter type syndrome. Both cases are characterized by hypokalemic metabolic alkalosis, hyperaldosteronism, hyperreninemia, and the manifestation of dehydration. Therefore, many experts still mistakenly confuse Gitelman’s syndrome with Bartter’s syndrome. However, they differ significantly. Gitelman's syndrome begins to appear in children from about 6 years old or much later and is characterized by a more benign course. Children burdened with the syndrome quickly get tired, they have muscle hypotension and muscle cramps. The main differences in laboratory tests are severe hypomagnesemia and hypocalciuria.
Bartter's pseudo-syndrome refers to conditions characterized by similar symptoms to Bartter’s, the main of which is hypokalemic metabolic alkalosis. But it is not accompanied by pathology from the renal tubules.
It can be caused by:
- long-term use of diuretics;
- a long high chloride diet;
- frequent vomiting;
- excessive consumption of laxatives;
- cystic fibrosis.
Differential diagnosis
The most characteristic symptom of Bartter’s syndrome is hypokalemia, therefore, with differential diagnosis, doctors should take into account primarily those diseases that lead to chronic hypokalemia. For instance:
- diseases associated with a decrease in potassium intake in the body, such as anorexia nervosa, protein malnutrition, loss of large amounts of potassium through the kidneys, digestive tract or skin (if there is enough of it in the diet);
- increased release of potassium ion into the cells (transmineralization), for example, with alkalosis, activation of beta-2 receptors (beta-2 agonists, increased sympathetic activity), consumption of phosphodiesterase inhibitors (e.g. caffeine or theophylline) or administration of insulin;
- loss of potassium by the kidneys, which is present in primary or secondary aldosteronism, Gitelman’s syndrome, Liddle’s syndrome, Cushing's syndrome, congenital adrenal hyperplasia;
- loss of potassium through the digestive tract, which occurs with diarrhea, vomiting, or when taking laxatives;
- loss of potassium through the skin - excessive sweating and burns.
Diagnostics
Congenital Bartter syndrome in children is usually diagnosed between 1 and 2 years of age, and Gitelman's syndrome is most often detected in adolescence. Diagnostics consists of laboratory tests - urine excretion of sodium, potassium and calcium is observed in the urinalysis; an assessment of the level of renin and aldosterone in the blood is also necessary. In rare cases, a kidney biopsy is performed.
Treatment
Because the disease is genetically determined, causal treatments do not exist. In the case of mild forms in which ion transporter dysfunction is small, the prognosis is usually good, patients can function normally.
Compensatory treatment for violations of the level of electrolytes and the level of renin and aldosterone gives good results. As a rule, patients should regularly take potassium supplements to maintain their blood levels above 3.5 meq / l. Sometimes magnesium and sodium supplements are needed.
In the treatment of neonatal Bartter syndrome, therapy is started through the infusion of saline solutions (NaCl, KCI). To reduce potassium loss, Spironolactone, Triamteren, Amyloride are administered.
Long-term treatment of Bartter's syndrome in adults can lead to a gradual deterioration in kidney function and the development of renal failure. In this case, dialysis or kidney transplantation is necessary.
Bartter's Syndrome: Clinical Recommendations
For people with the syndrome in question, it is very important to follow several rules, including the adequate consumption of water lost in excess with urine, especially during exercise and hot weather.
You must also understand that medications must be taken regularly to maintain electrolyte balance. In addition, patients should be well aware of which foods contain a large amount of potassium, and control their sufficient amount in the diet.
Gitelman syndrome treatment
Therapy focuses on maintaining normal concentrations of potassium, magnesium and chlorine in the blood. This is achieved by using a diet rich in potassium and sodium, and taking magnesium supplements (magnesium chloride is recommended). Magnesium itself also relieves symptoms of potassium deficiency. Some patients should take magnesium compounds throughout their lives. In case of symptoms of chondrocalcinosis, analgesics are additionally administered.
Most asymptomatic patients need medical (mostly nephrological) monitoring about 1-2 times a year. In other cases, the frequency of visits to a specialist depends on the severity of the patient's symptoms. The lives and functioning of people with this syndrome are usually the same as those of the rest of the healthy population. Only increased fatigue can adversely affect their daily activities.
Inheritance
The main risk factor is the presence of the disease in the family. The syndromes described above are hereditary, that is, abnormalities in the genetic material can be transmitted to children by their parents. Currently, if an abnormality is found in the fetal DNA, the disease cannot be prevented.
Now you know what the differences between Bartter and Gitelman syndrome in adults and children are and what these conditions are dangerous.