Preferred Specimen(s) 10 mL of well mixed 24-hour urine
Transport Container Plastic leak proof container
Instruction Please submit a 10 mL aliquot of a 24-hour collection. Refrigerate during and after collection. Collect urine with 25 mL of 6N HCl to maintain a pH below 3. Do not include first morning specimen; collect all subsequent voidings. The last sample collected should be the first morning specimen voided the following morning at the same time as the previous morning’s first voiding.
Record 24-hour urine volume on test request form and urine vial.
Transport Temperature Refrigerated 7 days
Reject Criteria Received at room temperature
Methodology Spectrophotometry
Clinical Significance Phosphorus is present in many foods with a mean intake of approximately 1.5 gm/day in adult men and 1.0 gm/day in adult women. Absorbed phosphate, under the influence of parathyroid hormone, is readily excreted by the kidney. Urinary phosphate measurement generally reflects dietary intake hence day-to-day excretion varies considerably.