Preferred Sample Type

Alkaline Phosphatase (ALP) Isoenzymes (APISO)

Suitable Specimen Types

  • Serum
1.0 mL blood

Specimen Transport

First class post to referral laboratory.

Sample Processing in Laboratory

Centrifuge and separate serum. Perform total ALP analysis before sending to referral laboratory.

Sample Preparation

Centrifuge sample and separate serum. Store separated serum at 4ºC prior to sending to referral laboratory.

Turnaround Time

2 weeks from date received by referral laboratory

Sample Stability


Alkaline Phosphatase (ALP) Isoenzymes (APISO)

General Information

Alkaline Phosphatase (ALP) in human serum originates from several sources including bone; liver; intestine and placenta. Because of the wide distribution, limited information can be obtained from a total ALP activity assay. The tissue source of elevated ALP in serum, however, can be determined by identifying the individual isoenzyme present in excess.

The individual ALP isoenzymes normally can be separated by electrophoresis according to charge differences. The separated ALP isoenzymes are visualised using a specific chromogenic substrate.

Patient Preparation



Test not required if total serum ALP is in the normal range.

PLEASE NOTE from 01/08/2012, ALP isoenzyme analysis is no longer performed in-house, specimens to be sent to referral laboratory.  All requests will be vetted by the Duty Biochemist.

Reference Range

Reported as a comment:


Predominantly liver isoenzyme present.


Predominantly bone isoenzyme present.


Both liver and bone isoenzymes are present in approximately equal concentrations.


Biliary isoenzyme also present.


Intestinal isoenzyme also present: this may indicate intestinal disease but also may occur in the absence of pathology in some individuals of blood group O and B after eating.


Alkaline phosphatase isoenzyme analysis is not indicated when the total alkaline phosphatase is not markedly raised.


  • EQA Scheme?: No
  • EQA Status:

    No EQA Scheme available

The laboratories at Heartlands Hospital, Good Hope Hospital and Solihull Hospital form part of the services provided by University Hospitals Birmingham and are UKAS (United Kingdom Accreditation Service) accredited to the ISO 15189:2012 standard. For a list of accredited tests and other information please visit the UKAS website using the following link:

  • Heartlands, Good Hope and Solihull Hospital pathology laboratories are a UKAS accredited medical laboratory No.8217
  • United Kingdom Health Security Agency laboratory is a UKAS accredited medical laboratory No.8213

Tests not appearing on the UKAS Schedule of Accreditation currently remain outside of our scope of accreditation. However, these tests have been validated to the same high standard as accredited tests and are performed by the same trained and competent staff.

For further test information, please visit the test database:

Protection of personal information - Laboratory Medicine comply with the Trust Data Protection policy and have procedures in place to allow the Directorate and its employees to comply with the Data Protection act  1998 and associated best practice and guidance.

For further information contact Louise Fallon, Quality Manager, 0121 424 1235