Pathology Handbook

Alkaline Phosphatase

Synonyms

ALP

Part of Profile

Liver Function Test, Bone.

Clinical Indications

ALP rises in the presence of bile duct obstruction (e.g. primary biliary cirrhosis, gallstones, bile duct strictures).   ALP is also elevated in bone disease where increased osteoblastic activity is involved (e.g. malignancy (not myeloma), osteomalacia, Pagets) 

Request Form

Request on ICE

Availability

On request

Turnaround Time

Same day

Specimen

Serum in gold-top vacutainer

Volume

2 ml

Container

Vacutainer gold top

Collection

No specific collection conditions

Causes for Rejection

Unlabelled or incorrectly labelled sample; not meeting specific criteria for analysis

Reference range

Adult: 30 - 130 IU/L.

Mild increases in ALP may be seen as a result of age-related changes, particularly in older women

Children: Refer to report for age-related reference range.  Levels in children may be mildly elevated during growth spurts.

Interpretation

Elevated ALP may be as a result of liver or bone disease. Certain medications may also cause rises in ALP. A normal gamma-GT may be used to exclude liver disease, but a raised gamma-GT does not exclude bone disease (since liver and bone disease may both be present).

In bone disease,  particularly high levels of ALP are seen in Paget's disease. It should be noted that rises in ALP are not seen in osteoporosis or myeloma as increased osteoblastic activity is not involved.

In young children, high levels of ALP may be due to transient hyperphosphatasaemia of childhood. Alkaline phosphatase isoenzyme analysis may indicated in these cases.