Calcium, Urine

Clinical Use

Use

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);1 idiopathic hypercalciuria,2 and especially, parathyroid disorders. Follow-up of patients on calcium therapy for osteopenia.

Special Instructions

Not provided.

Limitations

Urinary calcium levels may be decreased in patients on oral contraceptives. The test lacks specificity for diagnosing hyperparathyroidism when increased. It is also noted that five percent of the population may naturally have hypercalciuria. The test may not consistently distinguish hypercalciuria caused by different conditions.

Test Details

Methodology

Automated Analyzer (Clinical Chemistry)

Biomarkers

Calcium

Analyte

Calcium level

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

6874-2 - Calcium 24h Ur-mRate

Result Codes

18488-7 - Calcium 24h Ur-mCnc
6874-2 - Calcium 24h Ur-mRate

Result Turnaround Time

1 day

Specimen

Urine

Volume

25 mL aliquot

Minimum Volume

1 mL

Container

Plastic urine container with at least 10 mL 6N HCl (hydrochloric acid)

Collection Instructions

Instruct the patient to void at 8 AM and discard the specimen. Collect all urine including the final specimen voided at the end of the 24-hour collection period (8 AM the next morning). Secure the lid. Transport to the lab with full labeling on the container including patient's name, room number, date and time collection started and finished. pH must be <2.

Patient Preparation

The patient should be on a low calcium, neutral ash diet for three days prior to urine collection. Withdraw drugs affecting mineral metabolism, such as antacids, phosphates, diuretics, glucocorticoids, carbonic anhydrase inhibitors, and anticonvulsants, two to four weeks prior to and during collection if possible.