Phosphorus, Inorganic

Additional Information:

UFHPL Epic order code: LAB113

CPT Code(s):


Specimen Requirements:

Type: Serum or plasma

Container/Tube: Serum gel or heparinized plasma

Sample Volume: Submit full tube

Minimum Volume: 0.5 mL serum or plasma


  1. Send specimens in their original tubes.
  2. Centrifuge tubes if there is a delay in transport of more than 1 hour.

  • Samples are stable for up to 8 hours at 15 – 25°C.
  • Samples are stable for up to 7 days at 2 – 8ºC.

Unacceptable Conditions: Samples with moderate or marked hemolysis will be rejected.

Specimen Retention Time: 5 days


Measurements of inorganic phosphorus are used in the diagnosis and treatment of various disorders, including parathyroid gland and kidney diseases, as well as vitamin D imbalance.


This inorganic phosphorus method is based on a modification of the method developed by Daly and Ertingshausen in which inorganic phosphate reacts with molybdate to form a heteropoly acid complex. The use of a surfactant eliminates the need to prepare a protein free filtrate. The absorbance at 340/380 nm is directly proportional to the Inorganic Phosphorus level in the sample. (Package Insert, OSR General Chemistry BAOSR6x22.03, 2013-07)


Within 24 hours

Reference Values:

3.7 – 7.2 mg/dL