Vitamin D: This can cause nephrocalcinosis because of Vitamin D therapy because it increases the absorption of ingested calcium and bone resorption, resulting in hypercalcemia and hypercalciuria. Medullary nephrocalcinosis Medullary sponge kidney Distal renal tubular acidosis Hyperoxaluria Renal papillary necrosis And other causes of hypercalcemia (and thus hypercalciuria) Immobilization (leading to hypercalcemia and hypercalciuria) Milk-alkali syndrome Hypervitaminosis D Multiple myeloma Hypercalciuria without hypercalcemia These conditions can cause nephrocalcinosis in association with hypercalciuria without hypercalcemia: Distal renal tubular acidosis Medullary sponge kidney Neonatal nephrocalcinosis and loop diuretics Inherited tubulopathies Chronic hypokalemia Beta thalassemia Mechanism Nephrocalcinosis is caused by an increase in the urinary excretion of calcium, phosphate, and/or oxalate. Nephrocalcinosis is closely associated with nephrolithiasis, and patients frequently present with both conditions, however there have been cases where one occurs without the other. Calcium oxalate and calcium phosphate crystals form when the concentration of the reactants exceeds the limit. The deposits are collected in the inner medullary interstitium in the basement membranes of the thin limbs of the loop of Henle. The calcium phosphate plaques can enlarge into the surrounding interstitial tissue, or even rupture into the tubule lumen and can promote calcium oxalate stone formation. Diagnosis Nephrocalcinosis is diagnosed for the most part by imaging techniques. The imagings used are ultrasound (US), abdominal plain film and CT imaging. Of the 3 techniques CT and US are the more preferred. Nephrocalcinosis is considered present if at least two radiologists make the diagnosis on US and/or CT. In some cases a renal biopsy is done instead if imaging is not enough to confirm nephrocalcinosis. Once the diagnosis is confirmed additional testing is needed to find the underlying cause because the underlying condition may require treatment for reasons independent of nephrocalcinosis. These additional tests will measure serum, electrolytes, calcium, and phosphate, and the urine pH. If no underlying cause can be found then urine collection should be done for 24 hours and measurements of the excretion of calcium, phosphate, oxalate, citrate, and creatinine are looked at. Stages of nephrocalcinosis Chemical or Molecular nephrocalcinosis: Defined as a measurable increase in intracellular calcium concentrations, however, it is not visible through X-ray or microscopically. Microscopic nephrocalcinosis: Occurs when depositis are visible by light microscope by obtaining a tissue sample from a biopsy. However, this cannot be seen in an X-ray. Macroscopic nephrocalcinosis: Occurs when calcification can be seen through X-ray imaging. Treatment Increasing fluid intake to