Lab Test

Phosphorus, Urine

Urine Phosphorus

Test Codes

Antrim #19169, 24 Hour Urine: EPIC: LAB5448, SOFT: PO424, Random Urine: EPIC: LAB5447, SOFT: PHOSU


Note: 24 hour and random urine specimens MUST be collected separately. See below for collection criteria.

Specimen Collection Criteria

Collect: 24 hour urine or timed urine specimen with a 24 hour urine container with 15 mL of 6N Hydrochloric Acid added prior to the start of collection.
Also acceptable: Random urine specimen in a screw-capped container or another sterile collection cup with no preservative (Minimum: 30 mL)

  • Refer to the table of Urine Preservative Options when multiple tests are requested.
  • Keep 24 hour urine specimen iced or refrigerated during collection.
  • Include start and end dates and times for the collection period on the specimen container.
Urine Preservative Options
No Preservative
6N Hydrochloric Acid
Boric Acid (10g)
Sodium Carbonate
50% Acetic Acid

Physician Office/Draw Specimen Preparation

Maintain specimens refrigerated (2-8°C or 36-46°F) prior to transport.

Preparation for Courier Transport

Transport: Entire 24 hour urine collection, or random urine, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

Specimens not collected and processed as indicated. 

In-Lab Processing

Measure total volume of 24 hour urine specimen. Record total volume and collection start and end dates and times in the LIS system. Aliquot a minimum of 10 mL from the well-mixed 24 hour urine collection.


Specimen Stability for Testing:

Room temperature (20-26°C or 68-78.8°F): 4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): For longer storage.

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days (Royal Oak and Troy store an aliquot for 30 days.)


Farmington Hills Chemistry Laboratory
Grosse Pointe Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory
Troy Chemistry Laboratory


Sunday – Saturday.
Results available within 24 hours.

Reference Range

Urine Phosphorus: 0.3 – 1.3 g/24 hours.
Normal ranges for random urines or for collections other than 24 hours have not been established.

Test Methodology



  • Increased urine phosphorus levels are associated with hyperparathyroidism, vitamin D-resistant rickets, immobilization following paraplegia or fracture, vitamin D intoxication, renal tubular damage, familial hypophosphatemia, and nonrenal acidosis.
  • Decreased levels are associated with hypoparathyroidism, pseudohypoparathyroidism, and parathyroidectomy.

Clinical Utility

Inorganic phosphorus measurements aid in the diagnosis and management of various disorders, including parathyroid gland and kidney diseases, vitamin D imbalance and kidney stones.

CPT Codes



Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.