Section 11. Kidney and Urinary Tract Disorders

Chapter 146. Tubular and Cystic Kidney Disorders

Topics: Introduction | Renal Tubular Acidosis | Renal Glucosuria | Nephrogenic Diabetes Insipidus | Cystinuria | Fanconi's Syndrome | Hypophosphatemic Rickets | Hartnup Disease | Bartter's Syndrome | Liddle's Syndrome | Polycystic Kidney Disease | Medullary Cystic Disease | Medullary Sponge Kidney | Alport's Syndrome | Nail-Patella Syndrome

Bartter's Syndrome

In Bartter's syndrome, the kidneys excrete excessive amounts of electrolytes (potassium, sodium, and chloride), resulting in electrolyte abnormalities.

Bartter's syndrome is usually hereditary and is caused by a recessive gene; thus, a person with the disorder has inherited two recessive genes for the disorder, one from each parent. The abnormal gene causes the kidney to excrete excessive amounts of sodium, chloride, and potassium. The loss of sodium and chloride leads to mild dehydration, which causes the body to produce more renin and aldosterone. The increase in aldosterone increases potassium and acid secretion in the kidneys, leading to hypokalemia and metabolic alkalosis (see Section 12, Chapter 159).

Symptoms and Diagnosis

Children with Bartter's syndrome grow slowly and appear malnourished. They may have muscle weakness and excessive thirst, may produce large amounts of urine, and may be mentally retarded. The loss of sodium and chloride leads to chronic mild dehydration.

The diagnosis of Bartter's syndrome in young children is based on a physical examination and low levels of potassium, sodium, and chloride in the blood. However, similar findings occur when children with certain eating disorders, such as bulimia nervosa, self-induce vomiting and misuse diuretics.

Treatment

Many of the consequences of Bartter's syndrome can be prevented by taking potassium supplements and a drug that reduces excretion of potassium into the urine, such as spironolactone (which also blocks the action of aldosterone), triamterene, amiloride, captopril, propranolol, or nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin. Drinking adequate amounts of fluids is necessary to compensate for the excessive fluid losses.