Alkaline Phosphatase

CPT Code(s):



Alkaline phosphatase activity is determined by measuring the rate of conversion of p-nitro-phenylphosphate (pNPP) in the presence of 2-amino-2-methyl-1-propanol (AMP) at pH 10.4. The rate of change in absorbance due to the formation of pNP is measured bichromatically at 410/480 nm and is directly proportional to the ALP activity in the sample. (Package Insert, OSR General Chemistry, BAOSR6x04.03, 2014-04)


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Measurements of serum alkaline phosphatase are used in the diagnosis of hepatobiliary disorders and bone disease associated with increased osteoblastic activity. Certain conditions such as Hodgkin’s Disease, congestive heart failure and ulcerative colitis will produce moderate elevation in alkaline phosphatase levels. Non-pathologic elevations can be observed in third trimester of pregnancy.

Specimen Requirements:

Type: Serum or plasma

Container/Tube: Serum gel or heparinized plasma

Sample Volume: Submit full tubes.

Minimum volume: 0.5 mL serum or plasma


  1. Send specimens in their original tubes.
  2. If there is a delay in transport of >1 hour, centrifuge tube.

Storage: Samples are stable for up to 4 days at 2 – 8ºC.

Unacceptable Conditions: Samples with moderate or marked hemolysis will be rejected.
Specimen Retention Time: 5 days

Collection Procedure:


Reference Values:

Adults: 34 - 104 U/L

Interpretation Data:



UFHPL Test #: 20020

UFHPL Epic order code: LAB112

Reported Notes: