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The ALT ‘value’, or level, is more specific to the liver than the AST value because the AST value may also be high if there is muscle damage elsewhere in the body. Monitoring levels of these enzymes can help doctors assess how much liver scarring (fibrosis) there is in conditions such as non-alcohol related fatty liver disease (NAFLD) and alcohol-related liver disease.
- Tests, Diagnosis and Screening
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- Liver Conditions
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- Diet and Liver Disease
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- Tests, Diagnosis and Screening
May 1, 2024 · When the liver is damaged, ALT and AST levels can increase within hours and remain high for a few days after. ALT and AST levels can be raised in viral hepatitis, non alcoholic fatty liver disease (now known as metabolic dysfunction-associated steatotic liver disease), alcohol related liver disease, auto-immune hepatitis and drug-induced liver ...
- Introduction
- Why Check Lfts?
- Reference Ranges
- Alt / Ast
- Alp / GGT
- Bilirubin
- Albumin
- LFT Interpretation Method
- Further Investigations
- References
Liver function tests(LFTs) are among the most commonly ordered blood tests and include: 1. Alanine transaminase (ALT) 2. Aspartate aminotransferase (AST) 3. Alkaline phosphatase (ALP) 4. Gamma-glutamyltransferase (GGT) 5. Bilirubin 6. Albumin This guide gives an overview of LFTsand a structured approachto their interpretation.
LFTs can be requested for multiple reasons:1 1. To investigate patients with suspected liver disease 2. To monitor patients with confirmed liver disease (e.g. cirrhosis) 3. To monitor the effects of potentially hepatotoxic medications LFTs are often sent as part of a ‘baseline’ screening panel of investigations for patients presenting with a wide r...
Table 1. Liver function test reference ranges These reference ranges can varybetween laboratories, so always check local guidelines.
Alanine aminotransferase (ALT) andaspartate aminotransferase(AST) are enzymes found within liver cells at high concentrations. Raised ALT / AST levels in the blood occur in pathologies that cause liver cell (hepatocyte) inflammation or damage. Therefore, raised ALT / AST levels are a marker of hepatocellular injury. Common causes of hepatocellular ...
Serumalkaline phosphatase (ALP) is derived from biliary epithelial cells (cells lining the biliary tract) and bones.3 Raised ALP levels can therefore be caused by cholestasis orbone disease. Gamma-glutamyltransferase (GGT) is found in hepatocytes and also biliary epithelial cells.2 It is a non-specific buthighly sensitivemarker of liver damage and ...
Bilirubin is a waste product of haemoglobin breakdown. It is predominantly metabolised and excreted by the liver. Raised levels of bilirubin in the blood will lead to a yellowing of the skin, known as jaundice. Hint: Jaundice is usually absent until the bilirubin level exceeds 50 micromol/L.
Albumin is synthesised in the liver and helps to bind water, cations, fatty acids and bilirubin. It also plays a crucial role in maintaining the oncotic pressure of blood. Albumin is used as a non-specific marker of the synthetic functionof the liver. Albumin levels can fall due to: 1. Decreased albumin production: malnutrition, severe liver diseas...
Determine the pattern of LFT derangement
The pattern of ALT to ALP risecan indicate whether the pathology is primarily cholestatic or hepatocellular: 1. A greater than 10-fold increase in ALT and a less than 3-fold increase in ALP suggests a predominantly hepatocellular injury 2. Aless than 10-fold increase in ALT and a more than 3-fold increase in ALP suggests cholestasis 3. It is possible to have a mixed picture involving both hepatocellular injury and cholestasis An isolated ALP rise without a GGT rise should raise your suspicion...
Assess the bilirubin
Bilirubin is a marker of severity in acute cholestatic pathology and acute hepatocellular liver injuries. The presence of clinical jaundice is generally an indication of severe diseaserequiring urgent referral to secondary care for prompt assessment and management. An isolated bilirubin risewithout further LFT derangement suggests pre-hepatic jaundice or Gilbert’s disease.
Assess synthetic function
In severe hepatocellular injuries, the synthetic functions of the liver also become impaired, leading to decreased albumin. Coagulation studiesmay show prolonged prothrombin time, and in very severe disease, serum blood glucose may be low due to impaired gluconeogenesis. Hint: In chronic hepatocellular pathology (e.g. cirrhosis), the ALT / AST may return to within the normal range, however synthetic function of the liver can be markedly impaired.
Once the pattern of LFT derangement has been established, it is essential to determine the underlying cause. If cholestasis is suspected, an ultrasound should be arranged to assess the biliary tree for a potential site/cause of biliary obstruction. If hepatocellular injury is suspected, a liver ultrasound is generally arranged to assess for any str...
Coates P. Liver Function Tests. Australian Family Physician. March 2011. Available at [LINK].UpToDate. Approach to the patient with abnormal liver biochemical and function tests. May 2023. Available at [LINK].Patient.info Professional. Abnormal Liver Function Tests. July 2019. Available at [LINK].UpToDate. Bilirubin metabolism. October 2022. Available at [LINK].Jul 9, 2024 · The test measures ALT and AST, enzymes produced by the liver. These enzymes are used by the body to facilitate metabolism (the conversion of food into energy). When the liver is damaged, ALT and AST can leak into the bloodstream. High levels of ALT and AST in the blood are reliable markers for liver disease.
Jul 19, 2022 · Blood tests can explain nausea, pain, jaundice and more. Your liver is a master at multitasking. It digests food, processes nutrients and removes toxins, and does away with old red blood cells, as ...
Jul 23, 2022 · Liver blood tests are used to detect liver diseases such as fatty liver, cirrhosis, hepatitis, and liver failure. Understand the result with high, low, and normal results of AST and ALT. Symptoms of elevated or high liver enzymes in the blood include fever, abdominal pain, poor appetite, itching, and nausea. Elevated levels of AST and ALT may signify the level of liver damage and varies by person.
People also ask
What are AST and Alt tests?
What does AST mean on a blood test?
What does Alt mean on a blood test?
What causes high ALT / AST levels?
There are four main liver blood tests: 1. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) test. These are enzymes in your liver cells that can leak into your bloodstream if your liver is inflamed or damaged. High ALT and AST levels occur during liver infections (hepatitis) and also during liver scarring (fibrosis).
