C Urolithiasis
Definition
Urolithiasis, or “kidney stones,” refers to the presence of calculi, typically composed of calcium oxalate, in the urinary system. These calculi result from hypercalcemia or hyperoxaluria. Other types of stones include magnesium ammonium phosphate, calcium phosphate, and uric acid.
Pathophysiology
Causes of hypercalcemia and hypercalciuria are primarily hyperparathyroidism, vitamin D intoxication malignancies, and sarcoidosis. Small bowel bypass is associated with hyperoxaluria. Alterations in urine pH and the presence of metabolic disturbances can also result in formation of renal stones, which differ in composition from the typical oxalate variety.