Nephrocalcinosis

Definition

Nephrocalcinosis is a disorder in which there is excess calcium deposited in the kidneys.

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
• Medullary sponge kidney
• Primary hyperoxalurias
• 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
• Tuberculosis of the kidney and infections related to AIDS
• Vitamin D toxicity

This condition is relatively common in premature infants.

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 homrone
• 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 being deposited in the kidneys.

Measures should be taken to reduce abnormal levels of calcium, phosphate, and oxalate in the blood. Medications that cause calcium loss will usually be stopped.

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

Kidney stones should be treated.

Expectations (prognosis)

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

Although further deposits in the kidneys can be prevented with good treatment, deposits already formed usually cannot be eliminated. Extensive deposits of calcium in the kidneys does 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 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

Monk RD, Bushinsky DA. Kidney Stones. In: Kronenberg HM, Melmed, S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008: chap 29.

Nephrolithiasis and nephrocalcinosis. In: Feehally J, Floege J, Johnson RJ, eds. Comprehensive Clinical Nephrology. 3rd ed. Philadelphia, Pa: Mosby Elsevier; 2007.