The Calcium urine test reflects intake, rates of intestinal calcium absorption, bone resorption and renal loss. Those processes relate to parathyroid hormone and vitamin D levels. Evaluation of bone disease, calcium metabolism, renal stones (nephrolithiasis); idiopathic hypercalciuria, and especially, parathyroid disorders. Follow-up of patients on calcium therapy for osteopenia.
Urinary calcium results are more meaningful if the patient has been on a low calcium, neutral ash diet for three days prior to urine collection. Drugs affecting mineral metabolism should be withdrawn, if possible, two to four weeks prior to and during collection. These include antacids, phosphates, diuretics, glucocorticoids, carbonic anhydrase inhibitors, and anticonvulsants.
Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Transport the specimen promptly to the laboratory. Container must be labeled with patient’s full name, room number, date and time collection started, and date and time collection finished. pH must be <2.