Medullary nephrocalcinosis

Nephrocalcinosis is defined as the deposition of calcium salts in the renal parenchyma. It is classified according to the location (i.e., cortical or medullary). Medullary nephrocalcinosis appears as clusters of calcification in the pyramids. These calcifications involve the distal convoluted tubules in the loops of Henle. Diagnosing the underlying renal disease based on the appearance is usually difficult with exceptions including papillary necrosis due to analgesic abuse and medullary sponge kidneys (1). In papillary necrosis, the entire papilla may be calcified, while in medullary sponge kidney, there is a characteristic band of calcification in the renal pyramids.

Primary hyperparathyroidism is the single most common cause of nephrocalcinosis in adults. The classic clinical findings are sometimes referred to as "(abdominal) groans, stones, and bones." Distal RTA is the second most common cause of medullary nephrocalcinosis. Other causes of nephrocalcinosis are hypervitaminosis-D states , and other conditions such as medullary sponge kidney, and renal papillary necrosis.

CT is more effective than other imaging modalities such as plain radiography and ultrasound in detecting calcification and can be used to locate medullary versus cortical deposition (2).
Correlation between the extent of radiographically demonstrable nephrocalcinosis and the degree of renal impairment is limited .

Diuretics and dietary salt restriction can reduce renal calcium excretion in medullary nephrocalcinosis.