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Jan 5, 2024 · An AST test looks for blood levels of aspartate aminotransferase, an enzyme found mostly in the liver. Higher-than-average AST levels may be a sign of liver damage or liver disease, though there may be other causes at play.
- 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].Nov 23, 2023 · An AST blood test, or SGOT test, checks how much AST, a liver enzyme, is present in the blood. High levels of AST in the bloodstream could be a sign of liver damage, or cell damage in...
- Results from an AST blood test can help indicate liver health. If AST levels are high, it may also be a sign of: chronic hepatitis damage from alco...
- AST levels above 40 U/L can indicate liver inflammation, or damage to the heart, bones, or muscles. AST levels above 1,000 U/L may indicate liver i...
- Doctors may recommend certain lifestyle changes to lower liver enzymes, such as: limit or avoid alcohol eat a balanced diet exercise regularly quit...
ALT and AST are enzymes found in the liver cells (hepatocytes) which leak into the blood stream when the liver cells are damaged. They indicate the degree of inflammation present in the liver. Levels of ALT and AST are usually high in conditions such as hepatitis – possibly twenty to fifty times higher than normal.
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). 2. Albumin test.
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.
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Jul 9, 2024 · Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are two enzymes measured in a blood test to check the health of your liver. High AST and ALT levels are a general sign of a liver problem.
