OVERVIEW
Bart’s syndrome is characterized by hypokalemic alkalosis, increased blood renin and aldosterone but normal blood pressure, and hyperplasia and hypertrophy of the paraglomerular apparatus. Early manifestations include polyuria, irritable thirst, constipation, anorexia, and vomiting. 50% of cases occur in children under 5 years of age, and it has been suggested to be a clinical syndrome caused by mutations in ion channel genes. There are six clinical subtypes: Type I (neonatal/fetal), Type II (neonatal/fetal), Type III (classic), Type IV (with sensorineural deafness), Type V (with hypocalcemia) and Gitelman syndrome.
Etiology
The primary etiology of the disease is inconclusive. Types I, II, III, and IV Bartter syndrome and Gitelman syndrome are autosomal recessive disorders, and type V Bartter syndrome is an autosomal dominant disorder.
Symptoms
Bartter syndrome can be disseminated or familial, the clinical manifestations of this disease are mainly hypokalemic symptoms, complex and diverse different types of clinical manifestations. Type I and type II Bartter’s syndrome is characterized by fetal or neonatal onset. Fetal polyuria can lead to amniotic fluid overload and preterm delivery, and early neonatal polyuria is obvious and lasts for 4-6 weeks, and it can be accompanied by dehydration that can lead to life-threatening conditions, as well as growth retardation and hypoplasia, and some patients can have thinness, triangular face, large forehead, big eyes, fan ears, and ptosis. Symptoms of type III Barthes syndrome begin at 2 years of age, and in some cases may appear in the neonatal period, with polyuria, thirst, vomiting, and dehydration, low growth, constipation, and salt cravings, and may have a neonatal-type Barthes syndrome appearance. Type IV Barthes syndrome in addition to similar clinical manifestations with type I and II Barthes syndrome may also have sensorineural deafness, psychomotor block and hypotonia. In addition to the clinical manifestations of other Barthes syndromes, hypocalcemia may occur shortly after birth and lead to tics and convulsions in the hands and feet.The other types of Gitelman syndrome are slightly milder and usually asymptomatic in the neonatal period, but some children may exhibit muscle weakness, spasticity, tics and arthralgia, and so on.
Examination
1. Laboratory examination
Most cases have significant hypokalemia, usually below 2.5 mmol/L, and as low as 1.5 mmol/L. The majority of cases have significant hypokalemia.
2. Other auxiliary examinations
Routine imaging tests, such as X-ray, ultrasound and electrocardiogram, etc., and EEG and brain CT, etc., if necessary.
Diagnosis
Clinical manifestations are low chloride and low potassium alkalosis, hyperrenin hyperaldosteronism, normal blood pressure, and glomerular paraglomerular organ proliferation can be seen in renal pathologic examination.
Differential diagnosis
1. Primary aldosteronism
Hypokalemia and hyperaldosteronism may be present, but there is hypertension and hyporeninemia, sensitive to angiotensin response.
2. Pseudoaldosteronism (Liddle syndrome)
Also presents with hypokalemic metabolic alkalosis but with hypertension, hyporeninemia and hypoaldosteronism.
3. Pseudo-Bartter’s syndrome
Caused by abuse of diuretics, laxatives or prolonged diarrhea, loss of potassium and chloride, hypokalemia, hyperreninemia and hyperaldosteronemia, but discontinuation of the above medications improves the symptoms.
Complications
Hypokalemia, upright hypotension, mental retardation, convulsions, gout, rickets, renal calcification and progressive renal failure can be complicated.
Treatment
1. Correct low blood potassium
(1) Potassium supplementation Long-term high-dose oral potassium chloride to correct hypokalemia, but large doses can cause gastric upset and abdominal) diarrhea.
(2) Potassium-preserving diuretics Spironolactone or aminopterin.
2. Prostaglandin synthase inhibitors
Indomethacin Ibuprofen and aspirin can improve clinical symptoms and correct hyperreninemia and hyperaldosteronism. Indomethacin is the most effective and should be started in small doses. In cases resistant to indomethacin, ibuprofen can be applied instead.
3. Inhibition of renin-angiotensin system
(1) Angiotensin transferase inhibitor, captopril, has some efficacy.
(2) Propranolol β-adrenergic blocking drugs can reduce the activity of renin, but the effectiveness is not certain.
4. Correcting hypomagnesemia
Magnesium chloride is used to correct hypomagnesemia.
It is currently believed that the combination of the above drugs, such as potassium supplementation and potassium-preserving diuretics and small doses of indomethacin, is more effective than applying one drug alone.
Prognosis
Infantile onset of the disease is characterized by severe symptoms, mental retardation in some children, and death due to dehydration, electrolyte disorders, and infections; after the age of 5 years, almost all of them have growth retardation, and some of them have progressive renal insufficiency, or even develop chronic renal failure.
Prevention
As the cause of the disease is still uncertain, there is no definite preventive measure. After the diagnosis of the disease, active symptomatic treatment should be given to prevent complications.