Use

This quantitative test, performed with a random urine specimen, may help screen for hypercalciuria, an established risk factor for kidney stone formation. It may also assist in assessing metabolic disorders of calcium metabolism, such as hyperparathyroidism, bone disease, and idiopathic hypercalciuria. The calcium-to-creatinine ratio is included to adjust for urine concentration variation, although 24-hour urine specimens are generally preferred for diagnostic evaluation of hypercalciuria. Calcium metabolism is tightly regulated by parathyroid hormone and vitamin D; urinary calcium excretion reflects kidney tubular filtration and reabsorption as well as dietary intake, intestinal absorption, and bone resorption. Elevated urinary calcium may occur with idiopathic hypercalciuria, chronic kidney disease, vitamin D intoxication, Paget disease of bone, sarcoidosis, multiple myeloma, or metastatic cancers; reduced levels may be seen in hypoparathyroidism, vitamin D deficiency rickets, osteomalacia, or familial hypocalciuric hypercalcemia. Medications such as calcium supplements and loop diuretics may increase urinary calcium, whereas thiazide diuretics may decrease it. Results should be interpreted in the context of clinical history and examination findings.