Lab Test


Phosphate, PO4, Inorganic Phosphate

Test Codes

Antrim #17259, EPIC: LAB5099, SOFT: PHOS

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Contact Laboratory for acceptability of other tube types. 
See Minimum Pediatric Specimen Requirements for Microtainer® collection.

Physician Office/Draw Specimen Preparation

Let SST specimens clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged SST tube within two hours of collection. (Minimum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged SST tube, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL)

Rejection Criteria

Moderate to grossly hemolyzed specimens.

Red-top tubes with serum not separated from cells within two hours of collection.

In-Lab Processing

Let SST specimens clot 30-60 minutes. Centrifuge SST tubes and Microtainers® to separate serum from cells. Deliver immediately to the appropriate testing station.


Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


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


Sunday – Saturday, 24 hours a day.
STAT results available within 1 hour of receipt in the Laboratory.
Routine results available within 4 hours.

Reference Range

Age related reference range:

 Age  Range (mg/dL)
0-14 days 5.6 - 10.5
15 days - 1 year 4.8 - 8.4
1-4 years 4.3 - 6.8
5-12 years 4.1 - 5.9
13-15 years 3.2 - 6.2
16-18 years 2.9 - 5.0
19 years - Adult 2.3 - 4.4

Test Methodology



  • Serum or plasma phosphorus may be elevated in a number of conditions including renal failure, hypoparathyroidism, milk-alkali syndrome, diabetic ketoacidosis, dehydration, acromegaly, bone metastases and following cardiac resuscitation. Increases may also be found after strenuous exercise and in hemolyzed samples (these would normally be rejected by the Laboratory).
  • Decreased serum/plasma phosphorus occurs following ingestion of carbohydrates, IV administered glucose and during treatment of diabetic ketoacidosis (as phosphorus moves into cells). Low phosphorus levels are also seen with primary hyperparathyroidism, vitamin D deficiency, septicemia, renal tubular disorders, malabsorption, severe burns and in severely malnourished patients or patients receiving PO4-free fluids on a long term basis.
  • Problems associated with severe hypophosphatemia include respiratory failure, decreased cardiac function, increased incidence of sepsis and CNS signs/symptoms.

Clinical Utility

Measurement of inorganic phosphorus aids in the diagnosis and management of various disorders, including those involving the parathyroid gland, kidney, bone, and vitamin D metabolism.

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.