Nephrocalcinosis: The deposition of calcium (in the form of calcium phosphate and calcium oxalate) in the substance of the kidney, a process that can impair the function of the kidney function. The disorder may be symmetric or, in anatomic disorders such as medullary sponge kidney, involve only a single kidney.
Nephrocalcinosis is caused by a number of conditions including: the excess excretion of calcium by the kidney, renal tubular acidosis, medullary sponge kidney, hypercalcemia (high calcium levels in the blood), renal cortical necrosis, and tuberculosis. Nephrocalcinosis is relatively common in premature infants, partly from intrinsic kidney calcium losses and partly from enhanced calcium excretion when they are given diuretics. Other causes include hyperparathyroidism, sarcoidosis, oxalosis, papillary necrosis, chronic glomerulonephritis, transplant rejection, and trauma. Medications can cause calcinosis with acetazolamide, amphotericin B, and triamterene commonly implicated.
Fragments of calcium oxalate or calcium phosphate may break free from the kidney and provide nuclei for the formation of kidney stones (nephrolithiasis).
Nephrocalcinosis may eventually result in acute obstructive uropathy or chronic obstructive uropathy, leading to eventual kidney failure. The disorder is often discovered when symptoms of renal insufficiency/renal failure, obstructive uropathy, or urinary tract stones develop.