Introduction To Bartter Syndrome

Bartter syndrome is caused by an inborn autosomal recessive defect, in the Na-K-2Cl co transporter in the thick ascending limb of the loop of Henle, leading to NaCl and water wasting.

Clinical Symptoms
The patient presents with polyuria, polydipsia, episodes of dehydration, flattering growth and constipation. sometimes there may be maternal polyhydramnios with an affected fetus.

Pathophysiology
Since there is NaCl and water wasting the resultant ECF volume contraction causes secondary renin secretion and raised aldosterone levels, with avid Na and water reabsorption in the distal tubule and reciprocal K and H secretion into the urine. Imprtant to note is that blod pressure is normal. There is also increases renal prostaglandin E2 secretion.

The above changes produce the characteristic biochemical disturbance of hypochloraemic hpokalaemic alkalosis.

Diagnosis
Crucial to the diagnosis is the finding of inappropriately high levels of urinary Cl and Na- usually more than 20mmol/L ; urine Ca is normal or high.

Treatment
Therapy involves K supplementation combined with prostaglandin synthetase inhibitors, usually indomethacin.

Pseudo Bartter syndrome
It has the same plasma biochemistry – hypochloraemic hpokalaemic alkalosis but appropriately low levels of urine Cl and Na < 10mmol/L

Main causes are:

• Cystic fibrosis- sweat loss of NaCl and water.
• Congenital chloride diarrhea- gastrointestinal loss.
• Laxative abuse- gastrointestinal loss.
• Cyclical vomiting