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Alkaline Phosphatase
Also known as : [ALP]


Plasma/Serum
Test performed by: LabPLUS Automation


Specimen Collection

Sample stability:                          


PST4.5 mL PST Blood (Preferred)
Micro-PST0.5 mL Paediatric Micro-PST Blood (Preferred)
Heparin5 mL Heparin Blood
Plain4 mL Plain Blood
SST3.5 mL SST Blood
Microsample0.5 mL Paediatric Microsample Blood
Micro-heparin0.5 mL Paediatric Micro-heparin Blood
Reference Intervals

Serum/plasma ALP reference intervals have been updated on 05/12/17. The predominant change is in paediatrics, to better reflect the physiological changes seen during adolescent years.

While the analytical method has not changed for individual laboratories, this update has incorporated information from recent high-quality publications on population reference interval studies, recommendations by Australasian Association of Clinical Biochemists (AACB) and data mining of laboratory results from NZ adults. If previously used reference intervals are needed or to discuss this further, please contact a chemical pathologist (see below for contact details).

Units: U/L

Uncertainty of Measurement:    12% at levels under 25 U/L

                                                              6% at levels over 350 U/L

 

Age

Female

0 to <6 months

80 - 600

6 months to <10 years

80 - 450

10 to <13 years

45 - 460

13 to <15 years

45 - 300

15 to <22 years

45 - 150

22 to <50 years

40 - 110

50 to <60 years

40 - 120

60 years and over

40 - 130

Age

Male

0 to <6 months

80 - 600

6 months to <10 years

80 - 450

10 to <15 years

45 - 500

15 to <17 years

45 - 380

17 to <19 years

45 - 220

19 to <22 years

45 - 150

22 to <50 years

40 - 110

50 to <60 years

40 - 120

60 years and over

40 - 130

 

 



Turnaround Time: Within 3 hours
Diagnostic Use and Interpretation

This enzyme is present in bone, liver, and placenta. The ALP assay does not differentiate the source. To determine the source of a raised ALP, liver enzymes and P1NP are usually sufficient.  If the source of a raised ALP is still unclear, ALP isoenzymes can be performed.

Bone:

Changes occur with age, especially during childhood.  Increased levels of activity are found in rickets,  osteomalacia, secondary hyperparathyroidism,  healing fractures and Paget's disease. It is variably increased with malignant deposits in bone. 

ALP activity is high in infants, decreases during the second year, and remains increased until puberty. 

P1NP (procollagen-1 N-terminal propeptide) is an independent marker of bone turnover which is specific for bone (not increased in liver disease)

Liver: 

Increased ALP may be caused by any disease which causes cholestasis including tumours, cirrhosis, hepatitis, liver abscess, drugs or toxins (see Hepatotoxic drug reactions ). An increased ALP and GGT in the absence of a raised bilirubin may indicate mass lesions (e.g. secondary tumours) which leave sufficient unaffected liver for bilirubin excretion to continue at an adequate rate.

Placenta:

ALP from this source increases in the final trimester of pregnancy (up to 5x the upper limit of the reference interval).

Tumours:

Some tumours secrete the placental isoenzyme of ALP (Regan isoenzyne)

Isolated raised ALP

Benign familial hyperphosphatasemia  is a cause for a persistent isolated increased ALP and is seen at any age. This is an asymptomatic genetic variant; all other liver enzymes are normal, and there is no evidence for increased bone turnover (normal P1NP).  Family members may also have a raised ALP.

In transient hyperphosphatasaemia of infancy the ALP level may be very high (thousands), and typically persists for a few months. The pathogenesis is not known, but it has been suggested to follow viral infections.

See Alkaline Phosphatase Isoenzymes

See gamma Glutamyl Transferase


Contact Information

Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.

If the query concerns a specific patient please include the NHI number in your email.

If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).

Individual chemical pathologists may be contacted but will not be available at all times. 

After-hours : contact  Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.


Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402 

Dr Cam Kyle: CampbellK@adhb.govt.nz   ext 22052 

Dr Weldon Chiu: WeldonC@adhb.govt.nz   ext. 23427 

Dr Campbell Heron: CHeron@adhb.govt.nz   ext. 23427




Last updated at 10:54:56 24/01/2024