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Nephrocalcinosis

Definition

Nephrocalcinosis is a kidney disorder in which there is an increased amount of calcium in the kidneys.

Causes, incidence, and risk factors

Nephrocalcinosis may be caused by a number of conditions:

• Excess excretion of calcium by the kidney
• Renal tubular acidosis
• Medullary sponge kidney
• Hypercalcemia (high calcium levels in the blood)
• Renal cortical necrosis
• Tuberculosis

Pieces of of calcium oxalate or calcium phosphate may break free from the kidney. The pieces (deposits) enter the kidney tubules and areas in between them. The deposits may result in reduced kidney function. Pieces of calcium may lead to the formation of stones (nephrolithiasis).

This condition is relatively common in premature infants, partly from intrinsic kidney calcium losses and partly from enhanced calcium excretion when they are given loop diuretics.

Symptoms

There are generally no early symptoms. Later symptoms related to nephrocalcinosis and associated disorders may include:

• Blood in the urine
• Blood in the vomit or stools
• Changes in mental status
  • Drowsy, lethargic, hard to arouse
  • Delirium or confusion
  • Coma
• Decrease in the force of the urinary stream, stream small and weak
• Decrease in sensation, especially the hands or feet
• Easy bruising or bleeding
• Feeling of incomplete emptying of the bladder
• Flank pain or back pain
• Generalized swelling and fluid retention
• Increased urine volume or urine output, decreased
• Increased urinary frequency or urgency
• Nausea, vomiting
• Need to urinate at night (nocturia)
• Painful urination (burning or stinging with urination)
• Seizures
• Urinary hesitancy (difficulty initiating the flow of urine)
• Urinary incontinence

Signs and tests

An examination may indicate disorders that occur as a consequence of nephrocalcinosis. For example, it may be discovered when symptoms of renal insufficiency, kidney failure, obstructive uropathy, or urinary tract stones develop.

There may be signs of fluid overload, such as abnormal heart and lung sounds, if kidney function is poor.

Imaging tests can help diagnose this condition. Tests that may be done include:

• Abdominal CT scan
• Abdominal film

Other tests may be done to diagnose and determine the severity of associated disorders.

Treatment

The goal of treatment is to reduce symptoms. The cause of the disorder must be treated. If the cause is type 1 renal tubular acidosis, vitamin D and calcium should not be given to correct bone disorders associated with the condition because this will worsen nephrocalcinosis.

Medications that enhance calcium loss should be discontinued. Never discontinue any medications without consulting your health care provider.

Conditions that result from the disorder should be treated as appropriate.

Expectations (prognosis)

The outcome varies depending on the extent of complications and the cause of the disorder. Stones can result in obstructive uropathy, possibly leading to eventual kidney failure if they are not passed in the urine or removed.

Complications

• Acute renal failure
• Chronic renal failure
• Kidney stones
• Obstructive uropathy (acute or chronic, unilateral or bilateral)

Calling your health care provider

Call your health care provider if you have symptoms of nephrocalcinosis.

Emergency symptoms include suddenly decreased urine output and decreased consciousness.

Prevention

Prompt treatment of causative disorders, including renal tubular acidosis, may help prevent nephrocalcinosis.

Review Date:8/14/2007
Reviewed By:Charles Silberberg, DO, Private Practice specializing in Nephrology, Affiliated with New York Medical College, Division of Nephrology, Valhalla, NY. Review provided by VeriMed Healthcare Network.

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