Liver function tests are aimed at giving a picture of the 'state' of your liver. They are a sensitive way of looking for liver strain or liver damage, as they often show this well before you get any symptoms or problems with your liver. This means that the cause of liver strain or damage can be diagnosed and, often, reversed.
Liver function tests are also used for monitoring in cases of known liver inflammation, injury or disease. The liver is your largest internal organ. It sits in the tummy abdomen , under your diaphragm on the right-hand side. It is usually tucked under the ribs, which protect it, although in some people the edge of the liver protrudes slightly. If the liver is swollen, through inflammation or disease, it can swell out from under the ribs and make your tummy swollen.
The liver is a factory for the production and breakdown of carbohydrates, fats, proteins, hormones and other essential body chemicals, and helps dispose of waste products. This work is mainly carried out by liver cells hepatocytes.
Some of the most important functions include:. Each of these is discussed below. The liver performs hundreds of different functions, so there are many other possible tests that look at its health. These would normally be done if an abnormality is found with the basic liver function tests described here, or if a specific problem is suspected.
They might include:. The 'normal range' is a range of values given by the local laboratory for liver function tests. The range varies slightly between laboratories according to the measurement methods that they use. The 'normal' limits are defined by laboratories as the range of levels inside which 19 of every 20 people with healthy livers will fall.
This means that, for any one liver test, around 1 in 20 people with healthy livers will have a result that is slightly abnormal. There will, in the majority of cases, be nothing wrong with their liver; having a test that's just over the edge usually means nothing, as long as - crucially - there is only one slight abnormality out of the whole range of tests.
You should always discuss even a slightly abnormal result with your doctor. You are likely to find out that your liver tests are abnormal from your healthcare provider, who will tell you what you need to do next.
However, if you obtain your test results without explanation, you should contact your healthcare provider to discuss them. In many cases, a single, isolated, slightly abnormal liver function test in a well patient will not signify an underlying problem. However, some liver disorders, including early signs of overuse of alcohol, can produce slight changes especially at first , so it's important to be sure.
The NAFLD fibrosis score Table 3 uses clinical data to predict risk of liver-related complications and death from advanced disease. However, its use may be limited by operator experience and in patients with elevated body mass index.
Age, ALT level, AST level, body mass index, diabetes mellitus or glucose intolerance, platelet count, serum albumin level. Alcoholic Liver Disease. Excessive alcohol intake is the primary cause of liver-related mortality in western countries. This index differentiates the conditions based on ALT level, AST level, height, mean corpuscular volume, sex, and weight. Drug-Induced Liver Injury.
The true incidence of drug-induced liver injury is unknown and likely underreported, although it has been estimated at Information from references 25 and Statin-induced liver injuries are rare. Food and Drug Administration now recommends only baseline measurement of ALT and AST before initiation of statins, and does not recommend routine liver monitoring for patients taking statins. Viral Hepatitis. Hepatitis B and C are common causes of elevated transaminase levels. Preventive Services Task Force recommends screening high-risk patients with hepatitis B surface antigen and hepatitis C virus antibody testing.
Hereditary Hemochromatosis. Hereditary hemochromatosis is an autosomal recessive disease causing increased iron absorption in the intestines and release by tissue macrophages.
Mild, asymptomatic elevations in liver enzymes can occur because iron itself does not elicit a significant inflammatory response in the liver. Transferrin saturation and serum ferritin level should be measured to rule out hereditary hemochromatosis in patients with elevated transaminase levels. Alpha 1 -Antitrypsin Deficiency. Alpha 1 -antitrypsin deficiency is a genetic condition that primarily causes chronic lung and liver disease.
Diagnosis begins with testing for serum alpha 1 -antitrypsin deficiency. If levels are very low, protein phenotyping or genotyping to look for the PiZZ variant should follow. Autoimmune Hepatitis. The prevalence of autoimmune hepatitis is 11 to 17 per , persons. Hypergammaglobulinemia is common in patients with autoimmune hepatitis, with total immunoglobulin G levels generally 1.
Although antinuclear antibody testing is commonly ordered, it has lower sensitivity and specificity. Wilson Disease. Wilson disease is a rare autosomal recessive disorder, occurring in approximately one in 30, persons, and is related to ineffective copper metabolism. It usually occurs in Eastern Europeans younger than 35 years. A serum ceruloplasmin measurement is the initial test. Extrahepatic Causes. A number of extrahepatic sources of asymptomatic transaminase elevations may be considered based on the clinical picture.
A large prospective study performed in the United Kingdom evaluated nearly 1, primary care patients with abnormal transaminase levels or liver function testing for two years to determine the cause of the abnormalities.
Only 17 1. This study, along with guidelines, informs the evaluation of mildly elevated transaminase levels in primary care Figure 1. Algorithm for the management of mildly elevated liver transaminase levels. Information from references 3 through 6 , and This article updates previous articles on this topic by Oh and Hustead , 9 by Giboney , 44 and by Johnston.
Data Sources : A PubMed search was completed using the key terms elevated, liver function tests, transaminases, and aminotransferases. In addition, we used the key words nonalcoholic fatty liver disease, alcoholic liver disease, viral hepatitis, hemochromatosis, alpha 1 -antitrypsin deficiency, autoimmune hepatitis, and Wilson's disease alone or in combination with aminotransferases. Search dates: May 1, , to April 8, The views expressed in this manuscript are those of the authors and do not reflect the official policy or position of the Department of the Army, the Department of Defense, or the U.
Already a member or subscriber? Log in. Interested in AAFP membership? Learn more. Community Hospital. Address correspondence to Robert C. Reprints are not available from the authors. A systematic review of the prevalence of mildly abnormal liver function tests and associated health outcomes. Eur J Gastroenterol Hepatol. The prevalence and predictors of elevated serum aminotransferase activity in the United States in — Am J Gastroenterol.
Changes in the prevalence of the most common causes of chronic liver diseases in the United States from to Nitin J.
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Stephen Rashbaum, Dr. Long Nguyen, Dr. The symptoms of all of the strains are similar. Liver inflammation due to alcohol consumption is called alcoholic hepatitis. When drugs are the underlying cause, doctors call it toxic hepatitis. The symptoms of alcoholic and toxic hepatitis are similar to those of other strains of hepatitis.
If a person is experiencing symptoms of alcohol or drug use disorder, the doctor may check their liver enzyme levels and offer various forms of treatment and support. Cirrhosis is a type of liver damage.
A person with cirrhosis has permanent scarring of the liver, which can prevent it from working properly.
Cirrhosis may eventually lead to liver failure. Cirrhosis symptoms include fatigue and skin itching.
People are at risk of cirrhosis if they do not receive treatment for hepatitis or fatty liver disease. A blood test can show elevated liver enzymes. The blood test checks for raised levels of AST and ALT, which are enzymes that the liver releases when it becomes inflamed or damaged.
If a doctor finds that a person has raised AST or ALT levels, they are likely to carry out further tests to determine the underlying cause. The treatment for elevated liver enzymes will focus on managing the underlying condition causing the increased levels. The doctor may advise a person to make lifestyle changes to lose weight, such as:. Speaking with a nutritionist or even a personal trainer can help someone stay on track with their weight loss plan.
If a person has fatty liver disease due to alcohol consumption, the doctor will support them in reducing their alcohol intake. Treatments for hepatitis depend on whether it is acute or long term. A doctor may recommend the following treatments for acute hepatitis:.
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