Bartter's syndrome is a disease that belongs to the so-called tubulopathies. It consists in a congenital defect in the nephron and, secondarily, leads to hormonal and electrolyte disturbances as well as acid-base disturbances. What are the causes and symptoms of Bartter's syndrome? How is his treatment going?

Bartter's syndromeconcerns the structure of the kidney like the Henle loop. It is worth recalling a bit of physiology here, because then it will be easier to understand this disease. The Henle loop is one of the structures of the nephron (the basic structural and functional unit of the kidney) and is part of the renal tubule where final urine is formed. It owes its name to its discoverer, Jakob Henle. It is located between the proximal and distal tubules and consists of the descending and ascending limbs. The entire renal tubule is lined with a single-layer squamous epithelium. The epithelium of the descending arm is permeable to water, while the epithelium of the ascending arm is permeable to s alt ions. The urine is thus concentrated in the Henle loop because the body resists water loss and a large amount of it is absorbed from the primary urine.

Bartter's syndrome - what is it?

Tubulopathies are a rare disease involving impaired renal tubular function. This leads to an impairment of their resorptive or secretory function, with the glomerular filtration itself being normal or only slightly reduced. Bartter's syndrome belongs to congenital tubulopathies. There are three types of Bartter's syndrome:

  • Type I - caused by a mutation in the gene encoding the Na-K-2Cl cotransporter on the ascending arm of Henle's loop;
  • Type II - caused by mutation of the gene encoding the ROMK potassium channel;
  • Type III - caused by a mutation in the CIC-Kb gene encoding a chloride channel on the ascending arm of the Henle loop.

Bartter's syndrome consists of impaired sodium absorption in the ascending arm of the Henle loop. This leads to a number of anomalies. Increased amount of unabsorbed sodium "escapes" from the body, and hyponatremia leads to hypovolemia. Hypovolemia in turn activates the renin-angiotensin-aldosterone system. The increased concentration of aldosterone causes the exchange of sodium ions for potassium and hydrogen in the further structures of the renal tubule, i.e. the distal tubule.and summary. Hyperkaliuria, which is the increased excretion of potassium in the urine, leads to hypokalemia. Hypokalemia, in turn, causes metabolic alkalosis.

We can distinguish two forms of Bartter's syndrome: classic and neonatal. In the classic form, the symptoms of Bartter's syndrome may appear at any age, and they are mainly impaired physical development with significant growth deficiency, poor appetite, polyuria and polydipsia. In addition, in the classic form of Bartter's syndrome, vomiting, muscle weakness and mental retardation may appear. On the other hand, the neonatal form of Bartter's syndrome, as the name suggests, manifests itself immediately after birth. It is characterized by severe polyuria, which often leads to dehydration. In addition, there is hypercalciuria, nephrocalcinosis, and loss of sodium and chlorine with urine.

When should Bartter's syndrome be suspected?

As you can see, the clinical symptoms of Bartter's syndrome are quite non-specific and can sometimes resemble other diseases such as diabetes. Therefore, laboratory tests play a very important role in the diagnosis of Bartter's syndrome. They will reveal hypokalemia, non-respiratory alkalosis or increased plasma renin activity. In addition, there may be concomitant reduction in blood pressure.

What should we differentiate Bartter's syndrome with?

The most characteristic symptom of Bartter's syndrome is hypokalemia, so in the differential diagnosis we should first of all take into account those diseases that lead to chronic hypokalemia, for example:

  • diseases with reduced potassium supply to the body, such as anorexia nervosa, protein and energy malnutrition, the supply of the "correct" amount of potassium in a patient who loses it in an increased amount through the kidneys, digestive tract or skin;
  • increased "escape" of potassium ion to cells (transmineralization), e.g. in alkalosis, activation of beta-2 receptors (beta -2-mimetics, increased activity of the sympathetic nervous system, thyroid crisis), when consuming phosphodiesterase inhibitors (e.g. caffeine or theophylline) or insulin administration;
  • Renal potassium loss, which occurs in primary or secondary hyperaldosteronism, Gitelman's syndrome, Liddle's syndrome, Cushing's syndrome, congenital adrenal hyperplasia, proximal and distal tubular acidosis, hypomagnesaemia, use of diuretics and thiazides, glucocorticosteroids, glucocorticosteroids , amphotericin B or cisplatin;
  • loss of potassium through the gastrointestinal tract, which occurs in diarrhea, vomiting, VIPs, or taking laxatives;
  • losspotassium through the skin - excessive sweating and burns.

Bartter's syndrome - treatment

Bartter's syndrome is a congenital disease, therefore its causal treatment is impossible. In symptomatic treatment, however, we administer orally potassium chloride in the amount of 100-300 mmol / d in six portions. Sometimes magnesium supplementation is additionally required. By using indomethacin, thiamterene or spironolactone, potassium loss through the kidneys can be reduced. In addition, it may be beneficial to use drugs that inhibit renin formation, such as propranolol or ACEI.

Category:

Urology and Nephrology