The liver is a very important organ of our body. It performs most crucial and important functions which help in sustaining life. It is such an important organ that without it perhaps the body will not function. But, fortunately even if 75% of a liver is diseased or removed it functions because it has the amazing power of regenerating new liver tissues from existing healthy liver cells.
Liver is the largest organ in our body which works to keep us healthy. It carries out major functions like protein synthesis, detoxification and generation of biochemicals which aid digestion.
Liver function tests assess damage levels of a liver and indicate if impairment of its functions has occurred. Here are some useful particulars about Liver enzymes and about tests generally advised by Doctors to ensure normal functioning of liver.
Let us first see what the functions of Liver are:
FUNCTIONS OF LIVER
There are over 100 functions of liver. Given below are a few important ones.
• Stores vitamins, sugar and iron to provide your body with energy. • Controls the production and elimination of cholesterol. • Cleans your blood off waste products, drugs and other poisonous substances. • Induces clotting factors to stem excessive bleeding from cuts/injuries. • Produces immunising factors and removes bacteria from the bloodstream to combat infection. • Releases a substance called "bile" to help digest food and absorb important nutrients. • Processes digested food from the intestine. • Controls levels of fats, amino acids and glucose in the body. • Combats infections in the body. • Clears the blood off infectious particles and bacteria. • Neutralizes drugs and destroys toxins. • Breaks down food and turns it into energy. • Manufactures, breaks down and regulates numerous hormones including sex hormones. • Produces enzymes and forms proteins responsible for most chemical reactions in the body -- for example clotting of blood and repair of damaged tissues.
What are Liver Function Tests?
While performing various functions, the liver produces a number of chemicals that pass into the bloodstream and bile. Various liver disorders alter the level of these chemicals in blood. The level of some of these chemicals can be measured in a blood sample. Tests commonly conducted on a blood sample are called 'LFTs' (Liver Function Tests). These usually measure the following.
SGPT (serum glutamic pyruvate transaminase) or ALT (alanine transaminase):
It is an enzyme present in liver cells which helps to process proteins. When a cell is damaged it leaks this enzyme into the blood where it is measured.
Normal levels in blood: 5 – 40 IU/L
SGPT increases in the following conditions: • Viral hepatitis. • Gall bladder stones. • Fatty liver. • Cirrhosis of liver. • Alcoholism. • Drug toxicity (overdose of some medicines). • Liver cancer. • In some cases of Congestive heart failure.
SGOT (serum glutamic oxaloacetic transaminase) or AST (aspartate transaminase):
It is an enzyme which is normally present in liver, heart and skeletal muscles. It is released into the blood in excess when there is damage to either liver cell or muscle cells.
Normal levels in blood: 5 – 45 IU/L.
Some common causes of elevated SGOT are: • Acute stage of viral hepatitis. • Obstructive jaundice. • Acute myocardial infarction (heart attack). • Acute viral myocarditis. • Alcoholic liver disease. • Severe muscle trauma or necrosis. • Cirrhosis of liver.
BILIRUBIN:
Bilirubin is a brownish yellow substance found in bile. It is produced when the liver breaks down old red blood cells. Bilirubin is then removed from the body through stool (faeces) and gives stool its normal brown colour.
Bilirubin circulates in the bloodstream in two forms.
1. Indirect or unconjugated bilirubin:
This form of bilirubin does not dissolve in water. Indirect bilirubin travels through the bloodstream to the liver, where it takes a soluble form. It is also known as prehepatic or free bilirubin.
Normal values: 0.1 – 1.0 mg/dl (milligrams per deciliter)
2. Direct or conjugated bilirubin:
Direct bilirubin dissolves in water and is made by the liver from indirect bilirubin. It is also known as post hepatic bilirubin.
Normal values: 0.0 – 0.4 mg/dl
3. Total bilirubin and direct bilirubin levels are measured directly in the blood, whereas indirect bilirubin levels are derived from the total and direct bilirubin measurements.
Normal values: 0.1 – 1.2 mg/dl for total bilirubin.
Some common causes of elevated bilirubin levels are: • Acute viral hepatitis. • Alcoholic liver disease. • Gallstones in common bile duct. • Cholecystitis (inflammation of gall bladder). • Pancreatic cancer. • Haemolytic jaundice. • Obstructive jaundice. • Cirrhosis of liver. • Sickle cell anaemia. • Gilbert’s syndrome.
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