Nephrocalcinosis

Nephrocalcinosis is a kidney disorder involving deposition of calcium and oxalate or phosphate in the renal tubules and interstitium (the areas between the tubules). These deposits may result in reduced kidney function.

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

Fragments of calcium oxalate or calcium phosphate may break free from the kidney and provide nuclei for formation of stones (nephrolithiasis). This may result in obstructive uropathy, possibly leading to eventual kidney failure if the obstructing stones are not passed in the urine or removed. Nephrocalcinosis may therefore be discovered when symptoms of renal insufficiency/renal failure, obstructive uropathy, or urinary tract stones develop.

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.

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

• Increased urine volume or urine output, decreased
• Urinary hesitancy (difficulty initiating the flow of urine)
• Dribbling of urinary incontinence
• Decrease in the force of the urinary stream, stream small and weak
• Increased urinary frequency or urgency
• A need to urinate at night (nocturia)
• Painful urination (burning or stinging with urination)
• Feeling of incomplete emptying of the bladder
• Blood in the urine
• Flank pain or back pain
  • one or both sides
  • progressive
  • severe
  • spasm-like (colicky)
  • may radiate or move to lower in flank, pelvis, groin, genitals
• Nausea, vomiting
• Generalized swelling, fluid retention
• Decrease in sensation, especially the hands or feet
• Changes in mental status
  • drowsy, lethargic, hard to arouse
  • delirium or confusion
  • coma
• Seizures
• Blood in the vomit or stools
• Easy bruising or bleeding

An examination but may indicate disorders that occur as a consequence of nephrocalcinosis. There may be signs of fluid overload, such as abnormal heart and lung sounds, if kidney function is poor.

• An abdominal film shows renal calcification.
• An abdominal CT scan shows nephrocalcinosis.

Other tests may be performed to diagnose and determine the extent of associated disorders.

The goal of treatment is reduction of 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 excretion should be discontinued. Never discontinue any medications without consulting your health care provider.

Conditions that result from the disorder should be treated in their usual manner.

The outcome varies depending on the extent of complications and the cause of the disorder.

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

Call your health care provider if symptoms indicate that disorders associated with nephrocalcinosis may be present.

Emergency symptoms include suddenly decreased urine output, and decreased consciousness related to calcium levels and/or kidney failure.

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