What is Alkaline Phosphatase? Function & Normal Range

Alkaline Phosphatase

What is Alkaline Phosphatase? Function & Normal Range

Alkaline phosphatases are a group of isoenzymes, located on the outer layer of the cell membrane; they catalyze the hydrolysis of organic phosphate esters present in the extracellular space. Zinc and magnesium are important co-factors of this enzyme.

Although alkaline phosphatases are present in different body tissues and have different physiochemical properties, these are true isoenzymes because they catalyze the same reaction. In the liver, alkaline phosphatase is cytosolic and present in the canalicular membrane of the hepatocyte.

Alkaline phosphatase is present in decreasing concentrations in placenta, ileal mucosa, kidney, bone, and liver, but the majority of the alkaline phosphatase in serum (more than 80%) is released from liver and bone, and in small amounts from the intestine.

Even though alkaline phosphatases are found in many tissues throughout the body, their precise physiological function remains largely unknown.[1][2]

Alkaline phosphatases are classified as tissue-specific and tissue nonspecific types.

Alkaline phosphatases found in the intestine, placenta, and germinal tissue are tissue-specific, which means they are found only in the tissues where they are expressed in physiological conditions but may contribute to the circulating pool of serum alkaline phosphatase under specific situations when there is increased stimulation of their production.

The tissue-nonspecific alkaline phosphatase forms the majority of the fraction circulating in serum and therefore, is of clinical interest. It is encoded by a single gene and is expressed in the liver, bone, and kidneys.

Intestinal alkaline phosphatase is coded by a separate gene, which is different from the gene that codes for placental alkaline phosphatase and the Regan isoenzyme (which is produced in excess amounts in Hodgkin lymphoma). All tissue-nonspecific AP have the same amino acid sequence but different carbohydrate and lipid side chains; post-translational modifications confer their unique physicochemical properties.[3][4]

Serum alkaline phosphatase levels vary with age in normal individuals. During childhood and puberty, due to bone growth and development, levels are high.

The levels decrease in the 15 to 50-year age group, are slightly higher in men than in women, and rise again in old age (significant difference in gender distribution). The reasons for these normal variations are not known.

A positive correlation has been described with body weight and smoking, and there is an inverse correlation with height.[5][6][7]

In healthy individuals, the circulating enzyme is primarily derived from liver and bone, and in some individuals to a minimal extent from the intestinal tract.

In individuals with blood groups O and B, serum alkaline phosphatase levels increase after consuming a fatty meal, due to contribution from the intestinal tract.

As this elevation can persist for up to 12 hours in the serum, it is recommended to check the serum enzyme levels in a fasting state.

Alkaline phosphatase behaves any other serum protein. It has a half-life of 7 days, and clearance from serum is independent of bile duct patency or functional capacity of the liver. Tthe site of degradation of alkaline phosphatase is not known.

Serum alkaline phosphatase level may remain elevated for up to 1 week after resolution of biliary obstruction. The liver is the source in most patients with elevated enzyme levels. Increased osteoblastic activity seen in disorders of the bone or normally during periods of growth is the next ly contributor.

The influx of placental alkaline phosphatase in late third trimester contributes to the rise in pregnant women.

The mechanism of the increase in alkaline phosphatase in hepatobiliary disorders had been a matter of debate. It has been shown convincingly that it is due to increased enzyme synthesis and not to reduced hepatobiliary excretion of the enzyme. Increased hepatic enzyme activity has been demonstrated to parallel the rise in serum AP activity.

This occurs primarily due to increased translation of the mRNA of alkaline phosphatase (mediated by the rising bile acid concentration) and increased secretion of alkaline phosphatase into serum via canalicular leakage into the hepatic sinusoid. The mechanism by which it is released into the circulation has not been elucidated.

It has been reported that vesicles containing alkaline phosphatase, and many such enzymes bound to the sinusoidal membranes, are found in the serum of patients with cholestasis.

  Because alkaline phosphatase is newly synthesized in response to biliary obstruction, its serum level may be normal in the early phase of acute biliary obstruction even when the serum aminotransferases are already at their peak.

There are a number of clinical methods for determination of serum alkaline phosphatase levels. They differ by substrate used, ph of the alkaline buffer, and the “normal” values generated.

The tests in principle rely on the ability of the enzyme to hydrolyze phosphate esters. In the most widely used international method, p-nitrophenyl phosphate is used as the substrate, and an amino alcohol is used as a buffer.

The rate of release of p-nitrophenol or phosphate from the substrate is measured as a marker of alkaline phosphatase activity and results reported in international units per liter.

The different methods appear equally effective in the detection of abnormal values in various clinical diseases. Using multiples of the upper limit of normal is a simple way of comparing results obtained via different tests.

Electrophoresis does not reliably differentiate the isoenzymes as the electrophoretic mobility of bone and liver isoenzymes is only slightly different.

Electrophoresis on cellulose acetate, with the addition of heat inactivation, is a much reliable test than electrophoresis alone.

Polyacrylamide gel slab based separation provides accurate identification of the liver, bone, intestinal and placental isoenzymes; this test is, however, not widely available.

Patients with blood group O and B may be instructed to fast before the test to avoid contribution from the intestinal isoenzyme if there is an unexplained elevation of alkaline phosphatase on routine tests. A gold-top serum separator tube containing a clot activator and serum gel separator is used to collect the blood for analysis.

There are many potential analytic sources of error. Factors such as concentrations of phosphate, magnesium, citrate, type, and concentration of buffer maintenance of the correct temperature may affect the final result.

When alkaline phosphatase is the only liver biochemical test that is elevated (i.e.

, when the serum aminotransferases are within normal limits), or when alkaline phosphatase is disproportionately elevated compared to other liver biochemical tests, evaluation of the patient should be geared toward identifying the cause and the source for the isolated or disproportionate alkaline phosphatase elevation.

In asymptomatic patients with isolated elevation of serum alkaline phosphatase, it is important to identify the major source of abnormality.

As the alkaline phosphatases derived from the liver, bone, placenta, and intestines have different physicochemical properties, fractionation using electrophoresis can provide serum levels of specific isoenzymes. The results using current techniques, however, are often unreliable and inaccurate. Other methods that relied on the heat or urea denaturation of the different isoenzymes have poor sensitivity and specificity.

The current approach utilizes measurement of the activity of those enzymes which increase in concordance with the liver alkaline phosphatase such as 5’-nucleotidase (5NT) and gamma-glutamyl transpeptidase (GGTP).

These enzymes are not elevated in disorders of bone and correlate well with hepatobiliary disorders. Serum GGTP is very sensitive for biliary tract disease but is less specific for liver disorders.

The 5NT may be elevated in pregnant patients; however, in non-pregnant patients, it is fairly specific for liver disorder and correlates strongly with serum alkaline phosphatase of liver origin.

However, lack of an elevated 5NT in the presence of an elevated alkaline phosphatase does not rule out hepatobiliary disease as they do not rise concomitantly in early or mild hepatic injury.

The principal clinical value of measuring serum alkaline phosphatase lies in the diagnosis of cholestatic liver disease. Some of the highest elevations in alkaline phosphatases are seen in patients with cholestasis. Usually, four-fold of the upper limit of normal or greater elevation is seen in up to 75% of the patients with cholestasis, either intrahepatic or extrahepatic.

The degree of elevation is not helpful in distinguishing the two types.

Similar elevations are seen in biliary obstruction due to cancer (cholangiocarcinoma, pancreatic head adenocarcinoma, or ampullary adenocarcinoma), choledocholithiasis, biliary stricture, sclerosing cholangitis, or causes of intrahepatic cholestasis such as primary biliary cholangitis, drug-induced liver injury, chronic rejection of liver allografts, infiltrative liver disease (sarcoidosis, amyloidosis, tuberculosis and liver metastasis),severe alcoholic hepatitis causing steatonecrosis. Patients with AIDS may also have particularly high levels, either due to cholangiopathy from opportunistic infections such as cytomegalovirus, cryptosporidiosis, or granulomatous involvement of the liver from tuberculosis.

Moderate elevation (up to four times the upper limit of normal) of serum alkaline phosphatase is nonspecific as it can occur in a variety of conditions affecting the liver including cirrhosis, chronic hepatitis, viral hepatitis, congestive heart failure and ischemic cholangiopathy. Disorders that do not primarily involve the liver such as intra-abdominal infections, cholestasis of sepsis, Hodgkin lymphoma, myeloid metaplasia and osteomyelitis can also cause moderate elevation of serum alkaline phosphatase.

Primary or metastatic cancer raises serum alkaline phosphatase levels by local bile duct obstruction and increasing leakage of the liver isoenzyme.

Primary extrahepatic cancer does not necessarily have to involve the liver or the bone; rarely some tumors can produce their alkaline phosphatase (Hodgkin lymphoma secreting the Regan isoenzyme) or exert a paraneoplastic effect causing leakage of the hepatic isoenzyme into the circulation (Stauffer syndrome due to renal cell carcinoma).

Abnormally low levels can be useful clinically as they are seen in Wilson disease, especially when presenting in a fulminant form with hemolysis.

Zinc is a cofactor of Alkaline phosphatase, which gets displaced by copper in Wilson disease, a disorder of copper overload, thereby leading to low levels.

Other causes of low alkaline phosphatase levels are zinc deficiency, pernicious anemia, hypothyroidism, and congenital hypophosphatasia.

An extensive evaluation is often not needed in those patients who have only a mild elevation of serum alkaline phsophatase (less than 50% elevation). Such patients may be observed clinically with periodic monitoring of serum liver biochemical tests.

Whenever alkaline phosphatase levels are deemed to be abnormally elevated, further evaluation should be done to determine whether the source is hepatic or non-hepatic. Hepatic source for an elevated alkaline phosphatase level is supported by the concomitant elevation of either GGTP or 5NT.

Electrophoresis and other methods such as stability after heating cannot accurately differentiate the isoenzymes. As the hepatic alkaline phosphatase is more heat stable than bone alkaline phosphatase, alkaline phosphatase fractionation its heat stability is less reliable than GGTP or 5NT.

If the source is deemed to be non-hepatic, then evaluation of underlying undiagnosed disorder is the next step. An elevated bone alkaline phosphatase can occur in bone metastasis, Paget disease, osteogenic sarcoma, healing fractures, hyperparathyroidism, hyperthyroidism, and osteomalacia.

Elevated intestinal fraction tends to occur after a fatty meal and runs in families; this does not require additional evaluation. If the liver is suspected to be the source,  imaging of the biliary tree is necessary to differentiate between extrahepatic or intrahepatic cholestasis in addition to reviewing the medication list.

A right upper quadrant ultrasonography is often the first imaging study that is ordered. If the bile duct is dilated, either endoscopic retrograde cholangiopancreatography (ERCP) or magnetic resonance cholangiopancreatography (MRCP) is done depending on the clinical indication.

If the bile duct is not dilated, testing for serum antimitochondrial antibody (AMA) is suggested to evaluate for primary biliary cholangitis (PBC). If serum AMA is normal, evaluation for causes of intrahepatic cholestasis, AMA-negative PBC, sarcoidosis, and various other previously mentioned disorders should be performed. Liver biopsy is often the final test employed in such situations as it helps to identify the etiology of elevated serum alkaline phosphatase.

To access free multiple choice questions on this topic, click here.

1.Pinart M, Kunath F, Lieb V, Tsaur I, Wullich B, Schmidt S., German Prostate Cancer Consortium (DPKK). Prognostic models for predicting overall survival in metastatic castration-resistant prostate cancer: a systematic review. World J Urol. 2018 Dec 15; [PubMed: 30554274]2.van der Doelen MJ, Mehra N, Hermsen R, Janssen MJR, Gerritsen WR, van Oort IM. Patient Selection for Radium-223 Therapy in Patients With Bone Metastatic Castration-Resistant Prostate Cancer: New Recommendations and Future Perspectives. Clin Genitourin Cancer. 2019 Apr;17(2):79-87. [PubMed: 30558834]3.Castells L, Cassanello P, Muñiz F, de Castro MJ, Couce ML. Neonatal lethal hypophosphatasia: A case report and review of literature. Medicine (Baltimore). 2018 Nov;97(48):e13269. [PMC free article: PMC6283130] [PubMed: 30508915]4.Cristoferi L, Nardi A, Ronca V, Invernizzi P, Mells G, Carbone M. Prognostic models in primary biliary cholangitis. J. Autoimmun. 2018 Dec;95:171-178. [PubMed: 30420264]5.Azpiazu D, Gonzalo S, Villa-Bellosta R. Tissue Non-Specific Alkaline Phosphatase and Vascular Calcification: A Potential Therapeutic Target. Curr Cardiol Rev. 2019;15(2):91-95. [PMC free article: PMC6520574] [PubMed: 30381085]6.Brichacek AL, Brown CM. Alkaline phosphatase: a potential biomarker for stroke and implications for treatment. Metab Brain Dis. 2019 Feb;34(1):3-19. [PMC free article: PMC6351214] [PubMed: 30284677]7.Heinrich D, Bruland Ø, Guise TA, Suzuki H, Sartor O. Alkaline phosphatase in metastatic castration-resistant prostate cancer: reassessment of an older biomarker. Future Oncol. 2018 Oct;14(24):2543-2556. [PubMed: 29925281]

Source: https://www.ncbi.nlm.nih.gov/books/NBK459201/

ALP

What is Alkaline Phosphatase? Function & Normal Range

Alkaline phosphatase (ALP) is a protein found in all body tissues. Tissues with particularly high amounts of ALP include the liver, bile ducts, and bone.

A blood test can be done to measure the level of ALP.

See also: ALP isoenzyme test

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture

How to prepare for the test

You should not to eat or drink anything for 6 hours before the test, unless otherwise instructed by your doctor.

Many drugs affect the level of alkaline phosphatase in the blood. Your health care provider may tell you to stop taking certain drugs before the test. Never stop taking any medicine without first talking to your doctor. Drugs that may affect the ALP level may include:

  • Allopurinol
  • Antibiotics
  • Birth control pills
  • Certain diabetes medicines
  • Chlorpromazine
  • Cortisone
  • Male hormones
  • Methyldopa
  • Narcotic pain medicines
  • Nonsteroidal anti-inflammatory drugs (NSAIDs), used for arthritis and pain)
  • Propranolol
  • Tranquilizers
  • Tricyclic antidepressants

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

This test is done to diagnose liver or bone disease, or to see if treatments for those diseases are working. It may be included as part of a routine liver function test.

Normal Values

The normal range is 44 to 147 IU/L (international units per liter).

Normal values may vary slightly from laboratory to laboratory. They also can vary with age and gender. High levels of ALP are normally seen in children undergoing growth spurts and in pregnant women.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean

Higher-than-normal ALP levels may be due to:

  • Biliary obstruction
  • Bone disease
  • Eating a fatty meal if you have blood type O or B
  • Healing fracture
  • Hepatitis
  • Hyperparathyroidism
  • Leukemia
  • Liver disease
  • Lymphoma
  • Osteoblastic bone tumors
  • Osteomalacia
  • Paget's disease
  • Rickets
  • Sarcoidosis

Lower-than-normal ALP levels (hypophosphatasemia) may be due to:

  • Malnutrition
  • Protein deficiency
  • Wilson's disease

Additional conditions under which the test may be performed:

  • Alcoholic liver disease (hepatitis/cirrhosis)
  • Alcoholism
  • Biliary stricture
  • Gallstones
  • Giant cell (temporal, cranial) arteritis
  • Multiple endocrine neoplasia (MEN) II
  • Pancreatitis
  • Renal cell carcinoma

References

Berk PD, Korenblat KM. Approach to the patient with jaundice or abnormal liver test results. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 150.

Pratt DS. Liver chemistry and function tests. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 73.

Review Date: 5/30/2011

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Any duplication or distribution of the information contained herein is strictly prohibited.

Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Medical Center. Please discuss with your doctor any questions or concerns you may have.

Source: https://www.ucsfbenioffchildrens.org/tests/003470.html

Blood Sciences Test

What is Alkaline Phosphatase? Function & Normal Range

Age (up until) Up to 29 days

Age (up until) 29 days-16 years

Age (up until) 16 years-120 years

Test Usage

Alkaline phosphatase refers to a family of enzymes that catalyze hydrolysis of phosphate esters at an alkaline pH. ALP is present (in decreasing order of abundance) in placenta, intestine, kidney, bone and liver.

In adults, more than 80% of serum ALP activity derives from liver and bone. In late pregnancy, placental ALP is increased. In children and adolescents most serum ALP activity originates in osteoblasts and correlates with the rate of bone growth.

The serum half life is seven days.

Familial benign hyperphosphatasaemia shows as a raised ALP throughout life.

Several caveats must be remembered in interpreting ALP results.

  • ALP levels should ideally be measured after fasting because enzyme levels increase as much as 30 U/L after food ingestion. Patients with blood group O and B who are secretors can have increased ALP levels after eating a fatty meal because of the release of intestinal enzyme.
  • Africans have 10 to 15% higher ALP serum levels than Caucasians.
  • In children, ALP is increased up to 3 times the upper limit of normal and in pregnant patients it can be increased up to 2 times normal.
  • ALP levels may double following bone fracture.
  • Smokers have 10% higher ALP levels than nonsmokers do.
  • ALP levels fluctuate approximately 6% from week to week in a healthy individual.

ALP is most useful in diagnosing cholestatic liver diseases. Bile duct obstruction results in increased synthesis of ALP by bile duct epithelial cells and release of ALP into the serum.

Alkaline phosphatase may be increased even if only a few small bile ducts are obstructed and serum bilirubin is normal. Serum ALP often exceeds four times the upper limit of normal in extrahepatic and intrahepatic cholestasis.

The most common causes of extrahepatic cholestasis are pancreatic cancer, common duct stones and strictures, and primary sclerosing cholangitis.

Intrahepatic cholestasis is usually due to primary biliary cirrhosis or drug reactions (erythromycin, chlorpromazine, estrogens, and methyltestosterone). Patients with primary sclerosing cholangitis and primary biliary cirrhosis initially have elevated ALP and normal bilirubin levels.

When the ALP level is increased disproportionately to the bilirubin level (e.g. a bilirubin < 1.0 mg/dL and ALP > 1000 U/L), granulomatous or infiltrative diseases of the liver are ly. Possible diagnoses include sarcoidosis, fungal infections, tuberculosis, and lymphoma. ALP levels are also increased in hyperthyroidism, cardiac failure, lymphoma, and hypernephroma.

Lower ALP levels (< 3 times the upper limit of normal) are less specific for cholestatic liver disease and may be seen with hepatocellular diseases such as acute viral hepatitis, chronic hepatitis, and cirrhosis.

However, it is important to remember that incomplete obstruction by gallstones may produce mildly elevated ALP levels. Intrahepatic cholestasis secondary to anabolic steroids or birth control pills may cause mild increases in ALP.

Gamma glutamyltransferase (GGT) can be measured to determine if elevated ALP levels are of liver origin; increased GGT indicates that ALP is most ly from the liver.

Medications that have been reported to increase ALP include; allopurinol, anabolic steroids, captopril, carbamazepine, chlorpromazine, chlorpropamide, diltiazem, erythromycin, estrogens, flutamide, gold salts, methimazole, methyltestosterone, phenothiazines, phenylbutazone, phenytoin, quinidine, sulfonamides, tolazamide, tolbutamide, trimethoprim-sulfamethoxazole, valproic acid, and verapamil.

Sometimes it is useful to look at the relationship of ALP to bilirubin and lactate dehydrogenase (LD) levels.

PathologyALPBilirubinLD
Intra or extrahepatic cholestasisIncreasedIncreasedNormal
Focal benign cholestasisIncreasedNormalNormal
Focal malignant cholestasisIncreasedNormalIncreased

Osteoblastic bone disease can also increase serum ALP. The most common bone disorders associated with elevated ALP are; Paget’s disease, osteomalacia, hyperparathyroidism, osteogenic sarcoma, and bone metastases.

Low alkaline phosphatase levels have been reported in patients with magnesium deficiency, hypothyroidism, malnutrition, hemolytic anemia, Wilson’s Disease, post coronary bypass surgery, estrogen replacement therapy, and congenital hypophosphatasia. Blood transfusion causes transient decreases in ALP, due to chelation of cations by citrate.

Specimen requirement is one SST tube of blood.

If blood is collected in a citrate or EDTA tube, ALP activity will be almost totally inhibited due to the chelation of zinc and magnesium, which are necessary enzyme cofactors.

Availability

Local test

Can be added on to an existing request up to 4 days following sample receipt

Specimen Labelling Procedure

Source: https://www.exeterlaboratory.com/test/alkaline-phosphatase/

ALP (Alkaline Phosphatase) Isoenzyme

What is Alkaline Phosphatase? Function & Normal Range

Alkaline phosphatase (ALP) is an enzyme found in many body tissues such as liver, bile ducts, bone, and intestine. There are several different forms of ALP called isoenzymes. The structure of the enzyme depends on where in the body it is produced. This test is most often used to test ALP made in the tissues of the liver and bones.

The ALP isoenzyme test is a lab test that measures the amounts of different types of ALP in the blood.

The ALP test is a related test.

How the Test is Performed

A blood sample is needed. Most of the time blood is drawn from a vein located on the inside of the elbow or the back of the hand.

How to Prepare for the Test

You should not eat or drink anything for 10 to 12 hours before the test, unless your health care provider tells you to do so.

Many medicines can interfere with blood test results.

  • Your provider will tell you if you need to stop taking any medicines before you have this test.
  • DO NOT stop or change your medicines without talking to your provider first.

How the Test will Feel

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

Why the Test is Performed

When the ALP test result is high, you may need to have the ALP isoenzyme test. This test will help determine what part of the body is causing higher ALP levels.

This test may be used to diagnose or monitor:

  • Bone disease
  • Liver, gallbladder, or bile duct disease
  • Pain in the abdomen
  • Parathyroid gland disease
  • Vitamin D deficiency

It may also be done to check liver function and to see how medicines you take may affect your liver.

Normal Results

The normal value is 20 to 140 international units per liter (IU/L) or 33.400 to 233.800 microkat per liter (µKat/L).

Adults have lower levels of ALP than children. Bones that are still growing produce higher levels of ALP. During some growth spurts, levels can be as high as 500 IU/L or 835 µKat/L. For this reason, the test is usually not done in children, and abnormal results refer to adults.

The isoenzyme test results can reveal whether the increase is in “bone” ALP or “liver” ALP.

Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.

The example above shows the common measurement range for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

Higher-than-normal ALP levels:

  • Biliary obstruction
  • Bone disease
  • Eating a fatty meal if you have blood type O or B
  • Healing fracture
  • Hepatitis
  • Hyperparathyroidism
  • Leukemia
  • Liver disease
  • Lymphoma
  • Osteoblastic bone tumors
  • Osteomalacia
  • Paget disease
  • Rickets
  • Sarcoidosis

Lower-than-normal levels of ALP:

  • Hypophosphatasia
  • Malnutrition
  • Protein deficiency
  • Wilson disease

Levels that are only slightly higher than normal may not be a problem unless there are other signs of a disease or medical problem.

ALP – blood test

What is Alkaline Phosphatase? Function & Normal Range

Alkaline phosphatase (ALP) is a protein found in all body tissues. Tissues with higher amounts of ALP include the liver, bile ducts, and bone.

A blood test can be done to measure the level of ALP.

A related test is the ALP isoenzyme test.

A blood sample is needed. Most of the time blood is drawn from a vein located on the inside of the elbow or the back of the hand.

You should not to eat or drink anything for 6 hours before the test, unless your health care provider tells you otherwise.

Many medicines can interfere with blood test results.

  • Your provider will tell you if you need to stop taking any medicines before you have this test.
  • DO NOT stop or change your medicines without talking to your provider first.

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

This test may be done:

  • To diagnose liver or bone disease
  • To check, if treatments for those diseases are working
  • As part of a routine liver function test

The normal range is 44 to 147 international units per liter (IU/L) or 0.73 to 2.45 microkatal per liter (µkat/L).

Normal values may vary slightly from laboratory to laboratory. They also can vary with age and gender. High levels of ALP are normally seen in children undergoing growth spurts and in pregnant women.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

Abnormal results may be due to the following conditions:

Higher-than-normal ALP levels

Lower-than-normal ALP levels

  • Hypophosphatasia
  • Malnutrition
  • Protein deficiency
  • Wilson disease

Other conditions for which the test may be done:

Berk PD, Korenblat KM. Approach to the patient with jaundice or abnormal liver tests. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 147.

Fogel EL, Sherman S. Diseases of the gallbladder and bile ducts. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 155.

Martin P. Approach to the patient with liver disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 146.

Pincus MR, Abraham NZ. Interpreting laboratory results. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 8.

Last reviewed on: 4/29/2019

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Source: https://www.mountsinai.org/health-library/tests/alp-blood-test

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