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Represents a set of hereditary kidney disorders that cause an imbalance in the levels of potassium, sodium, chloride, and other molecules in the body.
It is a rare genetic defect in the thick portion of the ascending loop of Henle. It is characterized by hypokalaemia, metabolic alkalosis, and standard or low blood pressure.
Classification
Bartter’s syndrome has been classified according to the specific gene that causes the disease.
These different types of Bartter syndrome are classified according to their clinical phenotypes that share many physiological disorders.
But in turn, they differ in the symptoms, the age at which they occur, and the degree of urinary excretion of calcium, potassium, and prostaglandin.
There are many cases where patients have presented other variants that are believed to be variants associated with Bartter syndrome but have not yet been identified.
The type of electrolyte problem that the patient presents will determine his type of Bartter syndrome.
Cases have been found of patients who possess the characteristics of classic Bartter syndrome and associated Gitelman syndrome.
From the investigations carried out, it can be inferred that some of the patients have presented with classic Bartter syndrome.
Initially, they produce changes in the symptomatology as they get older and begin to present problems with magnesium, which is a symptom characteristic of Gitelman syndrome.
The causes of these changes in the category or the fact of presenting changed diagnoses of classic Bartter syndrome and Gitelman syndrome are currently unknown.
Within these types of Bartter syndrome are distinguished four essential types:
- Classic Bartter syndrome: It is caused by mutations in the CLCNKB gene
- Gitelman variant: Caused by mutations in the NCCT gene.
- Prenatal variant or hyperprostaglandin syndrome: Characterized by defects in the NKCC2 and ROMK genes
- Neonatal (or prenatal) Bartter syndrome with sensorineural deafness is caused by defects in the CLCNKB and CLCNKA chloride channel genes or its beta BSND subunit.
Classic Bartter syndrome and Gitelman syndrome involve a variation of the thick ascending part of the loop of Henle or dysfunction of the distal convoluted tubule.
Neonatal Bartter syndrome involves more severe dysfunction of the polyuric loop, and neonatal Bartter syndrome with sensorineural deafness presents distal tubular dysfunction.
Causes
Initially, Bartter syndrome was considered a vascular disease, but with the progress of the investigations, it was determined that it was a kidney problem.
It is associated with mutations of five genes, producing genetic defects inherited in an autosomal recessive manner.
This condition is caused by a defect in a section of the tubules in the kidneys that involves an inability to perform the reabsorption of sodium from the bloodstream.
It is caused by an increase in the production of the hormone aldosterone and produces an excessive elimination of potassium from the body through the urine.
This condition produces low serum potassium levels and an abnormal acid balance in the bloodstream called metabolic alkalosis.
symptom
Patients with Bartter syndrome share the following clinical symptoms, with some variations according to the phenotypic type:
- Deep hypokalemia has deficient levels of serum potassium.
- Considerable increase in the urinary excretion of potassium (K) and prostaglandins.
- Normal blood pressure and elevated levels of renin and aldosterone in plasma.
Contradictorily, high levels of renin and aldosterone cause an increase in blood pressure.
However, when the patient has Bartter syndrome, renin and aldosterone are elevated, but the patients do not present variations in their blood pressure.
- Hypochloremic metabolic alkalosis (low levels of serum chloride).
- Avascular resistance related to the pressor effects of exogenous angiotensin II.
- Asymmetric hyperplasia of the juxtaglomerular complex in the segment of the preferred arteriole.
- Increased urination (Polyuria), need to wake up at night to urinate (Nocturia) due to excessive loss of sodium chloride in the urine, which produces the need or craving to consume salt, and an increase in thirst (Polydipsia), constipation and dehydration.
- Generalized muscle weakness, fatigue, muscle spasms, and contractures (Tetany), with Chvostek sign and Trousseau sign, caused by low potassium levels in the bloodstream ( hypokalemia ).
- Mental confusion and vomiting.
- Sensorineural hearing loss.
- Nephrocalcinosis.
When the condition manifests before birth, there is an excessive presence or increase in the amniotic fluid surrounding the affected fetus called polyhydramnios.
Affected babies usually have birth problems, and premature births may occur.
Treatment
The treatment will depend on the type of syndrome but focuses on preventing potassium loss in the body.
The cure for Bartter syndrome is unknown. But some treatments consist of supplying supplements to balance potassium, sodium, and chloride levels in addition to the prescription of drugs to prevent urinary wear of these elements.
In children, growth hormones can be used to prevent short stature. Early diagnosis and appropriate treatment in children with Bartter syndrome can improve growth and neuro-intellectual development.
