Doctors often order and examine liver function tests, generally blood tests, to take a look at vital bodily functions that revolve around the liver.  The tests themselves focus on the clearing of bilirubin and the production of enzymes that indicate health problems. Liver cells produce many enzymes when in distress, and this quantity is easily measured. Production of these enzymes does not always indicate liver disease -- often, additional tests are required to complete the diagnosis.

Why is My Doctor Ordering These?

While occasionally a doctor will order them as part of basic physicals, more often these tests are ordered for patients more prone to liver problems, such as those who drink alcohol or smoke in excess. A doctor may also request a test due to the age of the individual. Liver health is vital to digestion and its function, like most, decreases over time.

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The Liver Affects Other Parts of the Body

The liver does the heavy lifting when ridding your body of waste and when it comes to normal digestion. The organ also relies on the kidneys, gallbladder, and other organs to help it do its job. When the liver's capacity to function slows, countless issues that can arise, caused by toxins left unexpelled.

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What are the Primary Threats to the Liver?

While obesity and genetic factors certainly affect the liver's function, the primary causes of liver issues are lifestyle decisions such as heavy drinking and unsterile body modifications. Parasitic infections and viruses have a disproportionate effect on the health of the liver and can cause a fast-progressing problem. Liver failure can take years, or happen nearly overnight.

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Symptoms Which May Prompt a Test

Symptoms fairly specific to the liver include jaundice or a general yellowing of the eyes and skin, swelling in the abdomen and lower legs, dark urine, chronic fatigue, loss of appetite, and pronounced bruising without significant injury. Any of these symptoms could prompt a doctor to order liver function tests.

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What is Bilirubin?

Bilirubin is a yellow substance that is a natural part of bile, but a buildup of it causes jaundice and is an early indicator of liver issues. The breakdown of red blood cells creates bilirubin and is a crucial factor in deciding to order liver function tests. While a urine test can measure it as well, the doctor will likely order blood tests to get a more accurate and significant understanding of potential imbalances.

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Liver Enzyme Tests

ALT and AST levels are measured to determine the amount of inflammation in the liver. Aminotransferases enzymes are present in hepatocytes (liver cells). If you have hepatitis, these numbers can reach as high as 50 times normal counts. ALP testing, alkaline phosphatase, are Gamma GT numbers are used to measure suspected damage to the bile ducts.

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Liver Protein Tests

The doctor is also likely to order total protein tests to measure globulin and albumin levels. The liver produces globulin to help it fight infections throughout the body. Low albumin levels are another a reliable indicator or liver damage. Prothrombin is a protein crucial to the clotting of blood and can also indicate problems.

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The Risks of Liver Function Tests

Unlike a biopsy, there is little danger in standard liver function tests. There is no needle inserted anywhere near the liver itself, but rather the doctor or nurse will draw blood from the arm like most blood tests.

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What is the Doctor Looking For?

This question depends on the reasons for the test in the first place. The doctor will examine the results and take into consideration the patient's gender, medical history, and age. If the doctor cannot make a clear diagnosis from the liver function test, the next step will likely be a liver biopsy.

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Liver Biopsy

If your blood tests suggest a more substantial cause of liver issues, expect a biopsy, to allow the doctor to get a better look at the severity of the problem. A percutaneous liver biopsy removes a small piece of tissue in the liver for laboratory study. Transjugular or laparoscopic options are available, with the former being most common.

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