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Liver Function Tests

Liver Function Tests


What are the basic functions of the liver?

The liver can be found in the right upper part of the abdominal fascia just under the rib cage.

The liver has several functions which are essential to life. Briefly, some of the important features of the human liver are:

  • Detoxification of blood
  • Generation of important clotting factors, albumin, and many other important proteins
  • Metabolizing (processing) medications and nutrition
  • Processing of waste products of hemoglobin and other tissues
  • Production of glucose (gluconeogenesis or sugar synthesis/release during starvation)

Which are common liver blood function tests?

Liver blood tests are a few of the most commonly performed blood tests. These tests can be used to assess liver acts or liver injury.

A first step in detecting liver damage is a simple blood test to ascertain the number of certain liver enzymes (proteins) from the blood.

Under normal circumstances, these enzymes mostly live inside the cells of the liver.

However, if the liver is hurt for any reason, these enzymes have been spilled into the blood flow.

Enzymes are proteins that are present throughout the entire body, each with an exceptional function. Enzymes help to speed up (catalyze) routine and critical chemical reactions in the body.

Among the most sensitive and widely used liver enzymes are aminotransferases. They include aspartate aminotransferase (AST or SGOT) and alanine aminotransferase (ALT or SGPT).

These enzymes are normally predominantly contained in liver cells and to a lesser level from the muscle tissues.

If the liver is damaged or damaged, then the liver tissues melt those enzymes into the bloodstream, increasing the AST and ALT enzyme blood levels and signaling liver disease.

Other blood tests pertaining to the liver are dimensions of a number of the additional enzymes found in the liver.

In addition to AST and ALT, alkaline phosphatase, 5′ nucleotidase, and gamma-glutamyl transpeptidase (GGT) are a few of the other enzymes found in the liver.

The focus of this article is principally on the most common liver enzymes, AST and ALT.

Liver Disease Symptoms:

The liver has multiple purposes. It makes many of the chemicals needed by the body function normally, it breaks down and detoxifies substances in your system, and it also functions as a storage device.

When the liver has been damaged from illness, medication, alcohol, or other factors., a person may have symptoms of liver disease like

  • Nausea and vomiting
  • Jaundice (yellowing of the skin)
  • Fatigue
  • Weakness
  • Excessive swelling or bleeding, and
  • Leg swelling

Which will be the aminotransferase enzymes (ALT, AST)?

The aminotransferase enzymes catalyze chemical reactions in which an amino group from 1 amino acid (amino acids are building blocks of proteins) is moved by a donor molecule to some recipient molecule, therefore, the titles”aminotransferases.”

Medical terms can sometimes be confusing, as is the case with these enzymes because they have synonymous names that commonly arise in both medical and non-medical articles. For example:

  • Still another title for aminotransferase is transaminase.
  • The enzyme aspartate aminotransferase (AST) is also called serum glutamic oxaloacetic transaminase (SGOT).
  • Alanine aminotransferase (ALT) is also known as serum glutamic pyruvic transaminase (SGPT).

To put things temporarily, AST = SGOT and ALT = SGPT; they’re enzymes produced by the liver and other kinds of cells.

Normally, where are AST and ALT (aminotransferase enzymes)?

AST (SGOT) is normally found in a variety of tissues including the liver, heart, muscle, kidney, as well as mind. It’s released into the serum when any one of these tissues is damaged.

As an instance, AST degree in serum is raised in heart attacks or with muscle trauma.

It’s therefore, not a highly specific indicator of liver injury as its elevation can happen as a result of other cells that are injured.

ALT (SGPT) is, by contrast, normally found chiefly in the liver. This isn’t to say it is exclusively found in the liver, but that’s where it’s most concentrated.

It’s released into the blood as the consequence of liver injury. Thus, it functions as a rather specific indicator of liver disease.

What are normal levels of both AST and ALT?

  • The normal selection of values for AST (SGOT) is about 5 to 40 units per liter of serum (the liquid part of the blood).
  • The typical selection of values for ALT (SGPT) is about 7 to 56 units per liter of serum.

However, the ranges of AST and ALT numbers may differ slightly depending upon the technique and protocols used by various laboratories worldwide.

However, normal reference ranges are routinely supplied by each laboratory and published with each patient’s individual report.

High ALT and AST levels can indicate liver problems but require a full test to be certain.

It must be highlighted that higher-than-normal heights of these liver enzymes shouldn’t be automatically equated with liver disorder.

What do high (raised ) liver tests (AST and ALT) imply?

AST (SGOT) and ALT (SGPT) are sensitive indicators of liver damage or harm from several kinds of diseases or conditions, and collectively they are termed liver tests or liver blood tests.

However, it has to be highlighted that higher-than-normal heights of the liver enzymes should not be automatically equated with liver disorder.

They might mean liver problems or they may not. For instance, elevations of these enzymes can occur with muscle damage.

The interpretation of elevated AST and ALT results is dependent upon the whole clinical evaluation of an individual, and so it’s best done by doctors experienced in assessing liver disease and muscle disease.

Furthermore, the exact levels of these liver enzyme tests do not correlate well with the degree of liver issues or the prognosis (outlook).

Therefore, the specific levels of AST (SGOT) and ALT (SGPT) cannot be used to find out the degree of liver disease or forecast the future outlook for liver functioning.

By way of instance, individuals with acute viral hepatitis A may develop very high AST and ALT levels (sometimes from the thousands of units/liter range), but most people with severe viral hepatitis A recover fully with no residual liver disorder.

Conversely, individuals with chronic hepatitis C infection typically have only a little elevation in their AST and ALT levels while having a significant liver injury and even advanced scarring of the liver (cirrhosis) from continuing minor inflammation of the liver.

Can AST and ALT test results suggest liver function?

It is important to clarify that ALT and AST amounts do not reflect the function of the liver, even though in the health care community and in clinical books they commonly, and wrongly, are referred to as liver function tests.

In conditions when AST and ALT are extremely raised, the liver still may operate correctly.

Consequently, in case you have”elevated liver enzymes” or a top or abnormal liver test, you need to ask your doctor exactly what all the evaluations suggest.

What blood tests are performed to discover liver function?

blood tests are performed to discover liver function
Blood tests are performed to discover liver function

The blood tests which really reflect liver function would be the following; normal values (ranges) recorded are for adult men – girls and children have similar but slightly different ranges of regular test values

Coagulation panel (prothrombin time or PT, and international normalized ratio or INR):

These tests measure blood’s ability for normal reduction and avoidance of swelling and bleeding.

This is the use of certain proteins called clotting factors that normally are generated from the liver.

Normal values are about 9.5 to 13.8 seconds.

Albumin degree (hypoalbuminemia):

Albumin is a really common protein found in the blood with a variety of functions.

Additionally, it is generated only in the liver, also when its levels are lower than normal it can be indicative of chronic liver disease or liver cirrhosis.

Naturally, many conditions other than liver disease also may cause low albumin levels. Normal values are about 3.5 to 5 g/dL.


This molecule is a byproduct of the routine destruction of red blood cells happening in the liver. It’s normally published as bile in the feces.

Elevation of the bilirubin can indicate liver malfunction.

However, other conditions with increased destruction of red blood cells can also lead to increased bilirubin levels despite normal liver functioning. Normal values are about 0.1 to 1.0 mg/dL.

Platelet count:

Low platelet count (thrombocytopenia) has several causes, among which can be advanced liver disease.

Normal platelet counts are approximately 150,000 to 400,000 per (µL).


Glucose level is maintained within the body by many different mechanisms.

The liver may discharge glucose in the blood for nourishment of different cells in the event of starvation with inadequate oral intake of glucose.

This process, called gluconeogenesis, is yet another major function of the liver.

Conversely, a lot of people with liver cirrhosis become glucose intolerant and create diabetes.

GGT (Gamma-glutamyl transpeptidase):

This receptor is thought to indicate possible liver damage; the higher the abnormal level, the more likely there is liver damage.

Normal levels of GGT are approximately 9 to 48 U/L.

ALP (alkaline phosphatase):

The liver synthesizes the highest quantities of the enzyme so high levels in the blood might indicate liver harm along with other causes.

Normal levels of ALP are about 45 to 115 U/L.

LD or LDH (Lactate dehydrogenase):

This receptor might be elevated in various types of diseases, such as liver disease. Normal levels are about 122 to 222U/L.

Notice that many hospitals and physician’s offices list a liver function panel as part of a lab workup.

These panels differ and might consist of AST, ALT plus a few or all of the evaluations listed above.

In addition, the normal panel values may vary somewhat, especially between mature men, women, and children so seeing the”normal” ranges of test values would be recommended, and a thorough discussion with the physician is necessary.

In addition, some clinicians recommend other tests such as serum ammonia and serum lactate levels in their panels.

There are different tests like serum ammonia and serum lactate levels in their panels.

There are home liver tests for blood hormone levels and liver function however, people using these tests must first discuss their usage and results with their health care professional.

What medications may cause increased liver enzyme tests (AST and ALT) levels?

A number of drugs can cause abnormal liver enzyme levels in some people.

Examples of a few of the common medications with possible liver toxicity include:

Pain relief medicines such as:

  • Aspirin,
  • Acetaminophen (Tylenol and others),
  • Diclofenac (Voltaren, Cataflam, Voltaren-XR), and

Anti-seizure medications for example:

  • Phenytoin (Dilantin),
  • Phenobarbital

Antibiotics such as:

  • Tetracyclines, (for example, tetracycline [Achromycin])
  • Trimethoprim (Trimpex; Proloprim, Primsol)
  • Fluconazole (Diflucan ) and a few other anti-fungals, etc..

Cholesterol-lowering drugs such as statins:

  • Lovastatin (Mevacor, Altocor),
  • Rosuvastatin (Crestor), and
  • Niacin

Cardiovascular drugs such as:

  • Hydralazine (Apresoline)
  • Quinidine (Quinaglute, Quinidex), etc..

Other drugs:

  • Antidepressant medication of the tricyclic type

With drug-induced liver enzyme abnormalities, the enzymes usually normalize weeks to months after stopping the drugs.

Typically, the doctor might want to track the individual’s liver enzymes over time to affirm that the values are normalizing.

What conditions can cause very high AST or ALT levels?

AST and ALT serum levels in some liver conditions can range anywhere from ten times the upper limits of normal to thousands of units/liter.

The highest rates of AST and ALT are present with disorders that cause the rapid departure of numerous liver cells (extensive hepatic necrosis).

Although this degree of liver enzymes altitude is not common, it can occur in these circumstances as:

  • Acute viral hepatitis A or B
  • Profound liver damage imposed by radicals as from an overdose of acetaminophen (brand-name Tylenol) or mushroom poisoning
  • The prolonged collapse of the circulatory system (shock) when the liver is deprived of new blood providing oxygen and nutrients

Additionally, quite high AST and ALT levels could be a result of acute muscle diseases.

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