ALKALINE PHOPHATASE Pactical Handout for 2nd year MBBS

8/9/2019 ALKALINE PHOPHATASE Pactical Handout for 2nd year MBBS

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Alkaline phosphatase (ALP)

Alkaline phosphatase is a hydrolase enzymeresponsible for removing phosphate groups

from many types of molecules, including nucleotides, proteins, and alkaloids. Theprocess of removing the phosphate group is called dephosphorylation.

It occurs in osteoblasts, hepatocytes, the kidneys, spleen, placenta, prostate, leukocytes

and small intestine.the liver-bone-kidney type is particularly important.

Physiology

In humans, alkaline phosphatase is present in all tissues throughout the entire body, but is

particularly concentrated in liver ,bile duct, kidney, bone, and the placenta. The optimalpH for the enzyme activity is pH=10 in standard conditions.

The enzyme is termed alkaline phosphatase because it works under alkaline (non-acidic)

conditions, as opposed to acid phosphatase

Why It Is Done

A test for alkaline phosphatase (ALP) is done to:

Check for liver disease or damage to the liver. Symptoms of liver disease can include

jaundice, belly pain, nausea, and vomiting. An ALP test may also be used to check the

liver when drugs that can damage the liver are taken.

Check bone problems (sometimes found on X-rays), such as rickets, osteomalacia,bone tumors, Paget's disease, or too much of the hormone that controls bone growth

(parathyroid hormone). The ALP level can be used to check how well treatment for

Paget's disease is working.

Check the cause of a high blood calcium level.
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Results

An alkaline phosphatase (ALP) test measures the amount of the enzyme ALP in the

blood.

Normal

Normal values may vary from lab to lab.

Alkaline phosphatase

Adults: 30126 units per liter (U/L)

Children: 30300 U/L

Women in the third trimester of pregnancy have high ALP levels because the placenta

makes ALP. Children normally have much higher ALP than adults because rapid bone

growth is normal in children and bones make ALP.

High ALP levels can show that thebile ducts are blocked.Levels are significantly higher

in children and pregnant women.

High values

Very high levels of ALP can be caused by liver problems, such as:

Hepatitis

Blockage of the bile ducts (obstructive jaundice),

G allstones,

C irrhosis,

Liver cancer, or Cancer that has spread (metastasized) to the liver from another part of the body.

High ALP levels can be caused by bone diseases, such as:

Paget's disease,

O steomalacia ,

R ickets,

Bone tumors,

Tumors that have spread from another part of the body to the bone

Hyperparathyroidism

Normal healing of a bone fracture can also raise ALP levels.
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Rare Causes:

Heart failure,

H eart attack ,

Infectious mononucleosis

KIdney cancer Se psis

Low values

A decreased serum alkaline phosphatase may be due to:

Zinc deficiency.

Hypothyroidism.

Vitamin C deficiency/Scurvy.

Folic acid deficiency.

Excess Vitamin D intake.

Low phosphorus levels (hypophosphatasia)

Celiac disease. Malnutrition with low protein assimilation (including low stomach acid

production/hypochlorhydria).

Insufficient Parathyroid gland function.

Pernicious anemia

Vitamin B6 insufficiency

What Affects the Test?

Reasons you may not be able to have the test or why the results may not be helpful

include:

Taking medicines that may damage the liver, such as some antibiotics, birth

control pills, long-term aspirin use, and oral diabetes medicines.

Being pregnant. Women in the third trimester of pregnancy have high ALP levels

because the placenta makes ALP.

Going through menopause. Postmenopausal women may have higher ALP levels

than women who still have menstrual cycles.

Your age. Children normally have much higher ALP levels than adults because

rapid bone growth is normal in children and bones make ALP.
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Using alcohol.

What to Think About

If the alkaline phosphatase level is high, a special test will help to find the cause.

This test is called alkaline phosphatase isoenzymes, or ALP isoenzymes.

The isoenzyme profile of alkaline phosphatases can be determined to see if the

elevation of alkaline phosphatase came primarily from liver (ALP-1), bone (ALP-2), or

elsewhere.

If liver disease is suspected, more blood tests, an ultrasound, or a CT scan are

generally recommended to find the problem.

Other tests to check liver function, such as alanine aminotransferase, aspartate

aminotransferase, and bilirubin, are often done at the same time as an alkaline

phosphatase (ALP) test. For more information, see the medical tests Alanine

Aminotransferase (ALT), Aspartate Aminotransferase (AST), and Bilirubin.

Gamma glutamyl transferase (GGT), or gamma glutamyl transpeptidase, may be

measured in the blood to check the difference between bone ALP and liver ALP. High

levels of GGT are present when the liver is damaged but not present with bone disease.

A high level of GGT may be caused by alcohol use or may mean that blocked bile ducts

are causing inflammation. The level of GGT may be high with the use of certain

medicines, such as phenytoin and phenobarbital. In some medical centers, a test that

measures a substance called 5-nucleotidase is done instead of the GGT test because it is

better at finding liver disease.


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SERUM ALKALINE PHOSPHATE ESTIMATION

PRINCIPLE:

Colorimetric assay in accordance with a standardized method.

ALP

P-Nitrophenylphosphate + H2O ---------------- Phosphate + p-Nitrophenol

Mg2+

In the presence of magnesium and zinc ions, p-nitrophenyl phosphate is hydrolyzed by

phopsphatases to form phosphate and p-nitrophenol. The p-nitrophenol released isproportional to the ALP activity and can be measured photometrically.

REAGENT:

R1: Diethanolamine buffer, pH 9.8

Magnesium sulfate

Detergents and stabilizers

R2:

p-nitrophenylphosphate

PREPARATION:

5 parts of R1 are mixed with one part R2. This gives working reagent.

SPECIMEN:

Collect serum using standard sampling tubes.

Heparinized plasma.

Centrifuge samples containing precipitate before performing assay.

TESTING PROCEDURE:

Materials provided:

Working solution as described above

Additional materials required:

Calibrators and controls as indicated below

0.9% NaCl


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MANUAL PROCEDURE:

Wave-length: 405nm(400-420nm)

Temperature: +250C/ +300C/ +370C

Cuvette: 1cm light pathZero adjustment: air or distilled water

Semi micro

Working reagent: 1000lSample: 20l

Mix and wait for 30 seconds. Read absorbance and start stopwatch simultaneously. Read

again absorbance after exactly 1, 2 and 3 minutes. Calculate A/min

CALCULATION:

1cm cuvette, 405nm A/min 2757 = ALP(U/l)

A1 = ___________________________

A2 = ___________________________

A3 = ___________________________

Factor = 2757

A = A1 + A2+ A3 x factor = ___________________________

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ALKALINE PHOPHATASE Pactical Handout for 2nd year MBBS