Lab Dept:


Test Name:


General Information

Lab Order Codes:

PO4 Note: Also included in Renal Panel (RENP)


PO4; Phosphate

CPT Codes:

84100 – Phosphorus inorganic (phosphate)

Test Includes:

Phosphorus concentration is reported in mg/dL.


Test Indications:

Useful for the evaluation of phosphorus metabolism and calcium/phosphorus balance. Phosphorus in the form of inorganic phosphate is important and widely distributed in the human body, 85% skeletal. Serum phosphorus concentrations are diet dependant.

Lab Testing Sections:


Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

1 hour

Special Instructions:



Specimen Type:

Whole blood


Green top (Li Heparin) tube, preferred
Alternate tube: Red, marble or gold top tube

Draw Volume:

0.6 mL blood

Processed Volume:

0.2 mL serum/plasma


Routine venipuncture. Mix tubes containing anticoagulant by gentle inversion.

Special Processing:

Lab Staff: Centrifuge specimen, remove serum/plasma aliquot and transfer  into a plastic sample cup. Store at refrigerated temperatures for up to 48 hours.

Patient Preparation:

Preferable, the patient should be fasting. Phosphorus levels fluctuate following meals.

Sample Rejection:

Mislabeled or unlabeled specimen


Reference Range:


Range (mg/dL)

0 – 4 days:

4.6 – 8.0 mg/dL

5 days – 3 years:

3.7 – 6.5 mg/dL

4 - 10 years:

3.6 – 5.6 mg/dL

11 – 15 years:

2.9 – 5.4 mg/dL

>15 years:

2.5 – 4.5 mg/dL

 Critical Values:

<2.0 or >10.0 mg/dL


Phosphorus concentrations may be increased by excess hemolysis or decreased by excess lipids.




Siemens Dimension Vista system Chem 2 Cal product insert, Siemens Healthcare Diagnostics, Inc. (2008-03) PN 7151150.001 – US

Jacobs & DeMott Laboratory Test Handbook (2001) Lexi-Comp, Inc, Hudson, OH, 5th Edition

Biorad Liquid Assayed Multiqual Control Product Insert Bio-Rad Laboratories, Irvine, CA 92618

Biorad Liquichek Urine Chemistry Control Product Insert Bio-Rad Laboratories, Irvine, CA 92618

Should acidification of urine be performed before the anaylsis of calcium, phosphate and magnesium in the presence of crystals?, Clin Chim Acta (2013) November 15; 426: 46-50. doi:10.1016/j.cca.2013.08.024. Epub 2013 Sep 5

Acidification and urine calcium; is it a preanalytical necessity? Ann Clin Biochem (2009) November 46 (Pt6): 484-7. doi:10.1258/acb.2009.009027. Epub 2009 Sep 3

Clinical Biochem Reference Range Handbook (2013) East Sussex Healthcare, Paul Eaton, 7/2/2013


7/21/2015: Vista update
2/9/2016: Update alt tube type
7/6/2016: Updated reference ranges