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

Medullary Sponge Kidney

Medullary sponge kidney is an uncommon disorder in which the urine-containing tubules of the kidneys are dilated.

Medullary sponge kidney is usually caused by a non-genetic abnormality that occurs during development of the fetus. Much less often, the abnormality is hereditary. Medullary sponge kidney causes no symptoms most of the time, but a person with the disorder is prone to developing painful kidney stones, blood in the urine, and kidney infections. Calcium deposits in the kidneys occur in more than half of the people with the disorder.

A doctor may suspect medullary sponge kidney based on the symptoms. X-rays of the kidneys reveal calcium deposits if there are any. The diagnosis can be confirmed by an imaging technique in which a radiopaque dye, which is visible on x-rays, is injected intravenously and then observed on x-rays as it is excreted by the kidneys. Ultrasound scans may help but may not detect tiny fluid-filled sacs (cysts) lying deep within the kidneys.

Most people do well without treatment. Treatment may be necessary if medullary sponge kidney causes calcium to deposit and form stones. Taking thiazide diuretics, drinking a lot of fluids, and eating a diet that is low in calcium may prevent stones from forming and obstructing the urinary tract. Surgery may be needed if the urinary tract becomes obstructed. Infections are treated with antibiotics.