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Test Code PH24U Phosphate, 24-Hour Urine (without creatinine) [11319X]

Specimen Required

10 mL urine aliquot from a well-mixed 24 hour collection collected in a plastic urine container

Specimen Minimum Volume

2 mL

Specimen Stability

Preserved Urine Room temperature: 6 months Refrigerated: 6 months Frozen: 6 months
Unpreserved Urine Room temperature: 48 hours Refrigerated: 7 days Frozen: 28 days

Report Available

Next Day

Method Name

Spectrophotometry (SP)


CPT code 81050 may be added at an additional charge for volume measurement

Collection Container / Tube

Preferred: Urine aliquot from a 24 hour collection in a urinalysis transport tube (yellow-top, blue fill line, preservative tube)
Urine aliquot from a 24 hour collection in a plastic leak-proof container – no preservative
Other Acceptable Container: None

Transport / Storage Conditions

Preserved Urine: Room temperature
Unpreserved Urine: Refrigerated (cold packs)

Special Instructions

Refrigerate during and after collection. Collect urine with 25 mL of 6N HCL to maintain a pH <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. Specify 24-hour total volume and collection duration on container and test requisition.

Reference Values

Male 360-1600 mg/24 h
Female 170-1200 mg/24 h

Day(s) Performed


CPT Codes


Clinical Reference

Phosphorus is present in many foods with a mean intake of approximately 1500 mg per day for adult males and about 1000 mg per day for adult females. Absorbed phosphate, under the influence of parathyroid hormone is readily excreted in the kidney. Measurement of urinary phosphorus generally reflects dietary intake, hence, day-to-day excretion may show considerable variation.