Definition

Nephrocalcinosis is a disorder in which there is too much calcium deposited in the kidneys. This condition is common in premature babies.

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Causes, incidence, and risk factors

Any disorder that leads to high levels of calcium in the blood or urine may lead to nephrocalcinosis. In nephrocalcinosis, calcium deposits form in the kidney tissue itself. Most of the time, both kidneys are affected.

Nephrocalcinosis is related to, but not the same as, kidney stones (nephrolithiasis).

Conditions that can cause nephrocalcinosis include:

• Alport syndome
• Bartter syndrome
• Chronic glomerulonephritis
• Familial hypomagnesemia
• Medullary sponge kidney
• Primary hyperoxaluria
• Renal transplant rejection
• Renal tubular acidosis
• Renal cortical necrosis

Other possible causes of nephrocalcinosis include:

• Ethylene glycol toxicity
• Hypercalcemia (excess calcium in the blood) due to hyperparathyroidism
• Use of certain medications, such as acetazolamide, amphotericin B, and triamterene
• Sarcoidosis
• Tuberculosis of the kidney and infections related to AIDS
• Vitamin D toxicity

Symptoms

There are generally no early symptoms of nephrocalcinosis, beyond those of the condition causing the problem.

People who also have kidney stones may have:

• Blood in the urine
• Fever and chills
• Nausea and vomiting
• Severe pain in the belly area, sides of the back (flank), groin, or testicles

Later symptoms related to nephrocalcinosis may be associated with chronic kidney failure.

Signs and tests

Nephrocalcinosis may be discovered when symptoms of renal insufficiency, kidney failure, obstructive uropathy, or urinary tract stones develop.

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

• Abdominal CT scan
• Ultrasound of the kidney

Other tests that may be done to diagnose and determine the severity of associated disorders include:

• Blood tests to check levels of calcium, phosphate, uric acid, and parathyroid hormone
• Urinalysis to see crystals and check for red blood cells
• 24-hour urine collection to measure acidity and levels of calcium, sodium, uric acid, oxalate, and citrate

Treatment

The goal of treatment is to reduce symptoms and prevent more calcium from collecting in the kidneys.

Treatment will involve methods to reduce abnormal levels of calcium, phosphate, and oxalate in the blood and urine.

If you take medicine that causes calcium loss, your doctor will usually tell you to stop taking it. Never stop taking any medicine before talking to your doctor.

Other symptoms, included kidney stones, should be treated as appropriate.

Expectations (prognosis)

What to expect depends on the complications and cause of the disorder.

Proper treatment may help prevent further deposits in the kidneys. However, there is usually no way to remove deposits that have already formed. Extensive deposits of calcium in the kidneys do NOT always mean severe damage to the kidneys.

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 know you have a disorder that causes high levels of calcium in your blood and urine, or if you develop symptoms of nephrocalcinosis.

Prevention

Prompt treatment of disorders that lead to nephrocalcinosis, including renal tubular acidosis, may help prevent it from developing.

References

Curhan GC. Nephrolithiasis. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 128.

Elder JS. Urinary lithiasis. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 541.

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