An alkaline phosphatase level test (ALP test) measures the amount of alkaline phosphatase enzyme in your bloodstream. The test requires a simple blood draw and is often a routine part of other blood tests.
Why Get Tested :
- Alkaline phosphatase is estimated to detect diseases of liver and bone.
- Alkaline phosphatase is the best marker for obstructive jaundice.
- Alkaline phosphatase is the marker:
When to Get Tested :
As part of a routine liver panel or when you have symptoms of a liver or bone disorder
When ALP Test Orderd :
An ALP test may be ordered as part of routine laboratory testing, often with a group of other tests called a liver panel. It is also usually ordered along with several other tests when a person has symptoms of a liver or bone disorder.
Signs and symptoms of liver involvement may include:
- Weakness, fatigue
- Loss of appetite
- Nausea, vomiting
- Abdominal swelling and/or pain
- Dark urine, light-colored stool
- Itching (pruritus)
Some examples of the signs and symptoms suggesting a bone disorder include:
- Bone and/or joint pain
- Increased frequency of fractures
- Deformed bones
Sample Required :
- It is done on the Serum of the patient.
- A fasting sample is a better choice.
- This test can be done on the random sample as well.
- How to get good serum: Take 3 to 5 ml of blood in the disposable syringe or in vacutainer. Keep the syringe for 15 to 30 minutes at 37 C and then centrifuge for 2 to 4 minutes to get the clear serum.
- Keep the sample refrigerated as soon as you separate the serum.
- Serum at 0 to 4 °C is stable for 2 to 3 days and at -25 °C is for one month.
- Perform the test as soon as possible because ALP activity increases 3 to 10% on standing at 25° C or 4 ° C for several hours.
Precautions for Sample :
- Storage At room temperature increases the ALP activity.
- Avoid EDTA and oxalate anticoagulant which decreases Alkaline phosphatase activity.
- If serum left at room temperature:
- Then there is a 1% increase in 6 hours.
- 3 to 6% in 1 to 4 days.
- Even may see an increase if refrigerated the serum which is 2%/day.
- Recent intake of food may increase the value.
- Values may be 25% higher after taking the high-fat meal.
- Drugs like allopurinol, antibiotics, colchicine, indomethacin, fluorides, isoniazid (INH), methotrexate, nicotinic acid, methyldopa, phenothiazine, and probenecid can increase the alkaline phosphatase level.
- Drugs like arsenal, cyanides, nitrofurantoin, and zinc salts may decrease the alkaline phosphatase level.
- Hemolysis may cause a slight increase in the ALP. ALP is 6 times more in the RBC than the serum.
Normal values :
- Children (3-15 yrs) : 104 – 390 IU / Ltr
- Adults : 25 – 147 IU / Ltr
ALP Decreased level seen in:
|Paget’s disease||10 to 25 times||Osteoblastic activity increase the ALP|
|Osteomalacia||Moderate increase||Level lowers with treatment|
|Rickets||2 to 4 times||Level lowers with treatment|
|Healing fracture||mild raised level|
|Fanconi’s syndrome||Mild to moderate increase|
|Primary and secondary hyperparathyroidism||mild to moderate increase|
|Osteogenic sarcoma||Very high level|
|Pregnancy third trimester||2 to 3-time increase||This is the placental origin|
|Children||1.5 to 2.5-times increase||Growing age|
|Metastatic tumor-like Ca prostate||raised level|
Other causes for raised level:
- It is also raised in old age and pregnancy.
- Hodgkin’s disease.
- Pulmonary and myocardial infarction.
- Hyperthyroidism (with a raised level of calcium).
- Chronic renal failure.
- Ulcerative colitis.
- ALP is increased during the last trimester of pregnancy and falls to normal within 3 to 6 months (postpartum).
ALP Decreased level seen in:
- Hypothyroidism ( Cretinism ).
- Milk-alkali syndrome.
- Celiac sprue.
- Scurvy ( vit.C deficiency ).
- Gross anemia.
- Deposition of radioactive material in the bone.
- In hypophosphatemia.
- Pernicious anemia.
- Nutritional deficiency of zinc or magnesium.
Interpretation of the Alkaline Phosphatase:
- If there is no jaundice and there is raised ALP indicates liver malignancy, drug-induced injury, rarely sarcoidosis and cyst.
- ALP presence in the urine indicates renal diseases like renal cell carcinoma, nephrosis, nephritis, SLE, and infarction.
- ALP raised in the third trimester of pregnancy indicates placental origin.
- In osteoclastic activity ALP is normal.
- In the osteoblastic activity, ALP is raised.