- Red top or green top (heparin)tube
- 5 mL of venous blood
Additional information on specimen collection:
- Do not freeze sample
- Do not use oxalate or citrate as anticoagulants
- Use fasted samples (meals promote increased activity)
- Reject if sample is not analyzed within 4 hr of collection. Alkaline phosphatase enzyme activity increases on standing
Alkaline phosphatase (ALP) is the sum of a number of isoenzymes found in all body tissues. High concentrations are present in the liver bile duct placenta intestines and bones.
The test is done to:
- Detect and identify skeletal diseases with marked osteoblastic activity
- Detect focal hepatic lesions
- Differentiate obstructive hepatobiliary tract disorders from hepatocellular disease
- Assess response to vitamin D therapy
- Substantiate the information from other liver function tests and GI enzyme tests
12 isoenzymes of ALP have been identified. The four main isoenzymes of clinical significance include:
- ALP1 of liver origin
- ALP2 of bone origin
- ALP3 of intestinal origin
- ALP4 of placental origin
Additional information:
- During the first few weeks of life ALP level rises to 5 to 6 times the value at birth. Then it decreases slowly till puberty. There is another spurt of increase at puberty. Then again it decreases to adult level by 16-20 years of age. In older adults the value again begins to rise.
- Higher in blacks than in whites and higher in men than in women (until menopause)
- Doubled during pregnancy rises to three times the normal during labor and returns to normal in 3 to 4 weeks after parturition
- May increase after a fatty meal in individuals with the blood group O and B
- Directly related to body mass and inversely to the height in adults
- Level is high in both obstructive and hepatocellular disorders in the liver
- Acts as a tumor marker for malignancies of the bone and liver and also gynecological malignancies
- Used alone the serum ALP levels may be misleading at times. An additional useful test is gamma glutamyl transpeptidase (GGT) test. GGT levels are increased in hepatobiliary diseases but not in uncomplicated bone diseases.
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
Reference ranges will be listed as Total alkaline phosphatase (T) Bone fraction (B) and Liver fraction (L).
| T (U/L) | B (U/L) | L (U/L) |
---|
Adult normals | 30-130 | 10-70 | 0-93 |
16-20 year olds (F) | 25-125 | 14-85 | 0-50 |
16-20 year olds (M) | 45-350 | 25-300 | 0-40 |
14 year olds (F) | 50-250 | 30-200 | 5-50 |
14 year olds (M) | 110-475 | 80-390 | 5-50 |
9-12 year olds (F) | 100-450 | 80-350 | 5-60 |
9-12 year olds (M) | 110-475 | 80-340 | 5-80 |
6 year olds | 70-375 | 50-300 | 5-75 |
1-5 year olds | 60-375 | 40-300 | 5-100 |
An elevation of Serum ALP to less than three times the upper range of normal is "non-specific " meaning that it often is not useful in establishing any specific diagnosis.
Increased serum ALP is seen in the following conditions:
Liver conditions:
Bone conditions:
- Acromegaly
- Bone growth
- Familial hyperphosphatemia
- Healing bone fractures
- Hyperparathyroidism
- Leukemia
- Malabsorption (secondary Hyperparathyroidism)
- Myelofibrosis
- Myeloma
- Osteogenic sarcoma
- Paget's disease (osteitis deformans)
- Pseudohyperparathyroidism
- Rickets
- Osteomalacia
Non-liver non-bone conditions:
Normal or increased serum ALP levels maybe seen in:
- Alcohol consumption (Chronic or acute)
- Cholecystitis/Cholangitis without common bile duct obstruction
- Gilbert Syndrome
- Myeloma
- Osteomalacia
- Rickets
Drugs that may increase serum ALP levels include:
- Acetaminophen (overdose)
- Acetylsalicylic acid (Aspirin)
- Allopurinol
- Amiodarone
- Amitriptyline
- Anticonvulsants
- Asparaginase
- Azathioprine
- Bromocriptine
- Captopril
- Cephalosporins
- Chloramphenicol
- Chlorothiazide
- Chlorpropamide
- Clindamycin
- Clofibrate
- Danazol
- Dapsone
- Enflurane
- Erythromycins
- Estrogens (in large doses)
- Ethambutol
- Ethionamide
- Fenofibrate
- Fluconazole
- Fluoroquinolones
- Foscarnet
- Gentamicin
- Glucocorticoids
- Gold salts
- Imipramine
- Interferon
- Interleukin-2
- Levamisole
- Levodopa
- Lincomycin
- Lithium
- Low molecular weight heparin
- Mercaptopurine
- Methyldopa
- Methyltestosterone
- Monoamine oxidase inhibitors
- Naproxen
- Nitrofurans
- Oral contraceptives
- Oral hypoglycemic gents
- Penicillins
- Phenothiazines
- Phenytoin
- Probenecid
- Procainamide
- Progesterone
- Propoxyphene
- Quinine
- Ranitidine
- Retinol
- Ritodrine
- Sulfonamides
- Sulfonylureas
- Tamoxifen
- Tetracyclines
- Tobramycin
- Verapamil
Low serum ALP levels are seen in:
Normal or decreased serum ALP levels maybe seen in:
Marked decline of the high ALP in pregnancy may indicate:
- Placental insufficiency
- Imminent fetal death
ALP level may be transiently low after blood transfusion. This may be due to zinc chelation.
Drugs that may decrease the serum ALP levels include:
- Alendronate
- Amidronate
- Calcitriol
- Clodronate
- Clofibrate
- Cyclosporine
- Etidronate
- Ipriflavone
- Norethisterone
- Oral contraceptives
- Tamoxifen
- Theophylline
- Ursodiol