Alternate Names: Familial juvenile nephrophthisis; Senior-Loken syndrome

Causes and Risks: Medullary cystic disease is a disorder involving the formation of cysts in the kidney medulla. The condition is inherited in most cases. The disorder causes an inability to concentrate the urine. This results in excessive fluid loss from the body, which is accompanied by loss of sodium. This is a "high output" type of chronic renal failure (renal failure with increased urine volume, but with all other aspects of kidney function decreased).

The disorder is rare, occurring in about 3 out of 100,000 people, mostly those under age 40. The disorder runs in families, and the inheritance patterns vary. (There is X-linked and autosomal dominant inheritance in different families. X-linked inheritance is carried on the X chromosome and is expressed in males that inherit the faulty gene from their mother and females that inherit the faulty gene from both parents. Females that only inherit the gene from one parent will not develop the disorder but can pass it on to their children. With autosomal dominance, if one parent has the gene for the disorder, 50% of the children will display symptoms). Risk factors include an individual or family history of medullary cystic disease, chronic renal failure, or increased urinary volume with excessive thirst.

Prevention: This is an inherited disorder, but the way it is inherited varies. Prevention may not be possible.

Symptoms:

• high urine output, unrelated to fluid intake
• urine pale colored
• nocturia (need to urinate at night)
• pale skin
• weakness
• weight loss
• nausea, vomiting
• general ill feeling
• fatigue
• headache
• frequent hiccups
• generalized itching (pruritus)
• easy bruising or bleeding (such as vomiting blood or blood in the stool)
• decreased alertness
  • drowsiness, somnolence, lethargy
  • confusion, delirium
  • coma
• muscle twitching or muscle cramps
• seizures
• increased skin pigmentation (skin may appear yellow or brown)
• decreased sensation in the hands, feet, or other areas

Signs and Tests: The blood pressure may be high, with mild to severe hypertension. A neurologic examination may show damage to multiple nerves. Abnormal heart or lung sounds may be heard through a stethoscope.

A CBC may show significant anemia (decreased red blood cells). A urinalysis shows dilute urine, excretion of small amounts of urine protein, or other abnormalities. (An abnormal urinalysis may occur 6 months to 10 or more years before symptoms appear.)

These tests also help confirm the diagnosis:

• high urine sodium
• progressively increasing creatinine levels
• progressively increasing BUN
• progressively decreasing creatinine clearance
• possibly increasing urine potassium
• arterial blood gases and blood chemistry showing metabolic acidosis
• IVP showing small kidneys
• abdominal ultrasound or abdominal CT scan showing small kidneys or multiple cysts on the kidneys
• renal biopsy showing interstitial nephritis or medullary cystic kidney

Treatment: Treatments focus on controlling symptoms, minimizing complications, and slowing the progression of the disease.

Adequate fluid intake should be encouraged. Dietary restrictions may slow the build-up of wastes in the bloodstream and control associated symptoms such as nausea and vomiting. The diet is often low protein, with high levels of carbohydrates to make up calories. Potassium, phosphorus, and other substances may be restricted. Salt should rarely be restricted in people with medullary cystic disease even if hypertension or fluid retention is present. Loss of sodium from the kidney can cause severe sodium depletion in the body. After evaluation of daily requirements, extra salt may be advised.

Blood transfusions or medications such as iron and erythropoietin may be needed to control anemia.

Associated diseases that cause or result from chronic renal failure must be controlled. Hypertension, congestive heart failure, chronic urinary tract infection, kidney stones, obstructions of the urinary tract (chronic urethral obstruction), glomerulonephritis, and other disorders should be treated as appropriate.

Dialysis or kidney transplantation may eventually be required.

Prognosis: There is no cure for chronic renal failure resulting from medullary cystic disease. Untreated, it usually progresses to end-stage renal disease. Chronic, lifelong treatment may control the symptoms of chronic renal failure.

Complications:

• hyponatremia
• end-stage renal disease
• pericarditis, cardiac tamponade
• platelet dysfunction
• gastrointestinal bleeding, ulcers
• hemorrhage
• anemia
• hepatitis B, hepatitis C, liver failure
• decreased functioning of white blood cells
• decreased functioning of immune system
• infection
• peripheral neuropathy
• seizures
• brain or nervous system damage, dementia
• weakening of the bones, fractures, joint disorders
• permanent skin pigmentation changes
• skin dryness, itching, or scratching with resultant skin infection
• changes in glucose metabolism
• changes in electrolyte levels, electrolyte abnormalities including hyperkalemia
• decreased libido, impotence
• miscarriage, menstrual irregularities, infertility
• congestive heart failure
• hypertension

Call for an appointment with your health care provider if symptoms indicate medullary cystic disease may be present.