Alkaline Phosphatase

What is alkaline phosphate

Alkaline phosphate is a blood enzyme. It aids in the breakdown of proteins in the body and comes in various forms depending on where it comes from.

Although the specific role of Alkaline phosphate in the body is unknown, experts assume it is involved in a variety of activities. Alkaline phosphate is present in the liver, bones, pregnant women’s placentas, intestines, kidneys, and other organs. Abnormal blood levels might indicate tissue injury or a disturbance in the body’s regular functions.

An Alkaline phosphate isoenzyme or Alkaline phosphate fractionation test is another form of Alkaline phosphate testing. Alkaline phosphate subtypes are evaluated in this assay. The location of Alkaline phosphate production in the body is indicated by these subtypes. While this type of testing can be useful, it is more technically difficult and hence less prevalent than standard Alkaline phosphate testing.

About the test

Alkaline phosphatase testing is used to see if your levels of this enzyme are normal. Alkaline phosphateblood tests can be used to screen for liver disorders and other health issues, as well as diagnose and monitor them.

Screening is the process of detecting health issues before they manifest themselves in the form of symptoms.Alkaline phosphate is seldom measured on its own in screening tests, although it is a common component of multi-measurement tests like a liver panel or a full metabolic panel (CMP). These tests may be ordered as part of a normal physical examination to screen for a variety of potential health issues.

Diagnosis is the process of determining the source of symptoms after they have appeared. When there are symptoms of potential liver issues, such as nausea and vomiting, jaundice, tiredness, abdominal discomfort, or unexplained weight loss, Alkaline phosphate is most commonly tested for diagnosis. It’s also commonly given if you’re experiencing signs of a suspected bone disease, such as bone pain, fracture risk, or irregular bone form. Alkaline phosphate testing as part of a liver panel or CMP may assist determine the source of nonspecific symptoms.The intensity or kind of a condition may be determined by the degree of Alkaline phosphateelevation. An Alkaline phosphate isoenzyme test can be used to establish where region of the body is affected and to diagnose the condition.

Monitoring is the process of tracking the progression of a disease or your reaction to therapy. An Alkaline phosphate test, which is frequently included in a panel, can be used to determine if liver disease or other diseases are improving, deteriorating, or remaining the same.

Purpose of the test

An Alkaline phosphate test can be used to assess the health of your liver and gallbladder, as well as to detect bone issues.

Gall bladder

Alkaline phosphate levels in the blood are checked as part of standard liver function and gallbladder testing. Symptoms such as jaundice, stomach discomfort, nausea, and vomiting may prompt your doctor to believe your liver or gallbladder is malfunctioning.

The Alkaline phosphate test can help you find out if you have:

cholera (inflammation of the liver)

Cirrhosis is a condition in which the liver is damaged (scarring of the liver)

cholecystitis is the inflammation of the bile ducts in the stomach (inflammation of the gallbladder)

bile duct blockage (from a gallstone, inflammation, or cancer)

If you’re taking a medication that could harm your liver, like acetaminophen, you might need an Alkaline phosphate test (Tylenol). Alkaline phosphate testing, which is usually done in conjunction with other liver function tests, is one way to check for that damage.


The Alkaline phosphate test can be used to diagnose a variety of bone conditions, including:

rickets is a condition in which children’s bones weaken or soften as a result of a substantial vitamin D or calcium deficit.

Osteomalacia is a weakening of the bones in adults caused by a lack of vitamin D, although it might also be caused by the body’s inability to handle and utilise vitamin D correctly.

Paget’s disease is a bone condition that causes significant difficulties with bone regeneration and breakdown.

Alkaline phosphate testing can also be used to look for cancer tumours, abnormal bone development, and vitamin D insufficiency. It can also be used to monitor therapy progress for any of the conditions mentioned above.

Test administration:

A tiny sample of blood from your arm is required for an Alkaline phosphate test. This is done at a clinical lab or in your doctor’s office.

A healthcare practitioner places an elastic band to the skin on the front side of your elbow to enable blood to pool in the vein after cleaning it with an antibiotic. The blood is then drawn into a tiny tube using a needle inserted into the vein. It is a painless and speedy procedure.


Your doctor will review the findings of your ALP test with you and advise you on what to do next once they are received.

High level:

Alkaline phosphate levels in your blood that are higher than usual may suggest an issue with your liver or gallbladder. Hepatitis, cirrhosis, liver cancer, gallstones, or a blockage in your bile ducts are all possible causes.

High levels might potentially suggest a bone problem such as rickets, Paget’s disease, bone cancer, or an overactive parathyroid gland, among other things.

Heart failure, kidney cancer, other cancers, mononucleosis, or bacterial infection are all possible causes of elevated Alkaline phosphate levels in rare circumstances.

A high Alkaline phosphate level can indicate a variety of illnesses, including liver and bone disorders. High Alkaline phosphate levels, on the other hand, may not always indicate a problem. Multiple factors may need to be considered when interpreting your test results:

The degree of elevation: Although very high levels are frequently associated with bile duct obstructions, high levels alone cannot differentiate between liver issues and other conditions.

Other test measurements: Alkaline phosphate is frequently measured in conjunction with other enzymes such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and/or 5′-nucleotidase (5′-NT), and the levels of Alkaline phosphate in relation to these enzymes can help determine the significance of your test result.

Your general health: Any symptoms you’re having, as well as your Alkaline phosphate levels, will be taken into account.

There can be some other conditions for elevated Alkaline phosphate level: 

Pregnant women, toddlers and adolescents, and elderly people all have greater levels of Alkaline phosphate In persons with specific blood types, Alkaline phosphate production in the gut might also rise after a fatty meal.

Low concentrations

Lower-than-normal Alkaline phosphate levels in the blood are uncommon, but they might suggest malnutrition, which can be caused by celiac disease or a vitamin and mineral deficit.

Malnutrition, nutritional shortages, hypothyroidism, and a few uncommon hereditary diseases that impair Alkaline phosphate or liver function can all result in abnormally low Alkaline phosphate levels.

Risks of the test:

Having your blood taken poses relatively few dangers.

Bruising surrounding the puncture site is possible but can be prevented by applying pressure to the area.

Phlebitis (vein inflammation) can occur in uncommon instances. If this happens, apply a warm compress to the affected area until the swelling subsides.

If you have any bleeding problems or are on blood thinners, tell your doctor before your blood is drawn.

Critical significance:

The main clinical benefit of testing blood alkaline phosphatase is to diagnose cholestatic liver disease, as individuals with cholestasis have some of the highest alkaline phosphatase levels. Up to 75 percent of patients with cholestasis, whether intrahepatic or extrahepatic, have a four-fold or greater elevation of the upper limit of normal. The difference between the two kinds is not helped by elevation. Similar elevations are seen in biliary obstruction caused by cancer (cholangiocarcinoma, pancreatic head adenocarcinoma, or ampullary adenocarcinoma), choledocholithiasis, biliary stricture, sclerosing cholangitis, or causes of intrahepatic cholestasis like primary biliary cholangitis, drug-induced liver injury, chronic rejection of liver Patients with AIDS may have particularly high levels, either as a result of cholangiopathy caused by opportunistic infections like cytomegalovirus or as a result of tuberculosis-related granulomatous liver involvement.

Similar elevations can occur in biliary obstruction caused by cancer (cholangiocarcinoma, pancreatic head adenocarcinoma, or ampullary carcinoma). Moderate elevation (up to four times the upper limit of normal) of serum alkaline phosphatase is nonspecific and can occur in cirrhosis, chronic hepatitis, viral hepatitis, congestive heart failure, and ischemic cholangiocarcinoma.

By obstructing the bile duct and increasing leakage of the liver isoenzyme, primary or metastatic malignancy elevates blood alkaline phosphatase levels. Some cancers can manufacture their own alkaline phosphatase (Hodgkin lymphoma secreting the Regan isoenzyme) or have a paraneoplastic impact, inducing hepatic isoenzyme leakage into the blood (Stauffer syndrome due to renal cell carcinoma)

In Wilson’s illness, especially when presenting in a fulminant form with hemolysis, abnormally low levels might be beneficial clinically. Zinc is a cofactor of Alkaline phosphatase, which is replaced by copper in Wilson’s disease, a copper overload condition, resulting in low levels of zinc. Zinc deficiency, pernicious anaemia, hypothyroidism, and congenital hypophosphatasia are some of the other reasons of low alkaline phosphatase levels.

When a patient’s serum alkaline phosphatase level is only slightly elevated, a thorough examination is often not required (less than 50 percent elevation). Serum liver biochemical tests can be used to monitor such patients on a regular basis. When alkaline phosphatase levels are abnormally high, further investigation is needed to determine whether the cause is hepatic or non-hepatic. The simultaneous elevation of either GGT or 5NT suggests a hepatic source for an elevated alkaline phosphatase level. If the source isn’t hepatic, the next step is to determine if there’s an underlying, undiagnosed disorder.