Liver is the most important organ of human body & it is located in the right upper portion of the abdominal cavity just beneath the rib cage. The liver has many functions that are vital to life. Briefly, some of the important functions of the human liver
The basic functions of the liver
• Detoxification of blood
• Production of important clotting factors, albumin, and many other important proteins
• Metabolizing (processing) medications and nutrients
• Processing of waste products of hemoglobin and other cells
• Storing of vitamins, fat, cholesterol, and bile
• Production of glucose (gluconeogenesis or glucose synthesis/release during starvation)
The common liver blood function tests
Liver blood tests are some of the most commonly performed blood tests. These tests can be used to assess liver functions or liver injury. An initial step in detecting liver damage is a simple blood test to determine the level of certain liver enzymes (proteins) in the blood. Under normal circumstances, these enzymes mostly reside within the cells of the liver. But when the liver is injured for any reason, these enzymes are spilled into the blood stream. Enzymes are proteins that are present throughout the body, each with a unique function. Enzymes help to speed up routine and vital chemical reactions in the body.Among the most sensitive and widely used liver enzymes are the aminotransferases. They include aspartate aminotransferase (AST or SGOT) and alanine aminotransferase (ALT or SGPT). These enzymes are normally predominantly contained within liver cells and to a lesser degree in the muscle cells. If the liver is injured or damaged, the liver cells spill these enzymes into the blood, raising the AST and ALT enzyme blood levels and signaling liver disease.
Other blood tests pertaining to the liver are measurements of some of the other enzymes found the liver. In addition to AST and ALT, alkaline phosphatase, 5′ nucleotidase, and gamma-glutamyl transpeptidase (GGT) are a few of the other enzymes located in the liver, the most common liver enzymes, AST and ALT.
Liver Disease Symptoms
The liver has multiple functions. It makes many of the chemicals required by the body to function normally, it breaks down and detoxifies substances in the body, and it also acts as a storage unit. When the liver is damaged from disease, medication, alcohol, or other factors., a person may have symptoms of liver disease such as :
• nausea and vomiting
• jaundice (yellowing of the skin),
• shortness of brearth
Aminotransferases enzymes (ALT, AST)?
The aminotransferases enzymes catalyze chemical reactions in which an amino group from one amino acid (amino acids are building blocks of proteins) is transferred from a donor molecule to a recipient molecule, hence, the names “aminotransferases.”
Medical terms can sometimes be confusing, as is the case with these enzymes because they have interchangeable names that commonly appear in both medical and non-medical articles. For example:
• Another name for aminotransferase is transaminase.
• The enzyme aspartate aminotransferase (AST) is also known as serum glutamic oxaloacetic transaminase (SGOT).
• Alanine aminotransferase (ALT) is also known as serum glutamic pyruvic transaminase (SGP
AST (SGOT) is normally found in a variety of tissues including liver, heart, muscle, kidney, and the brain. It is released into the serum when any one of these tissues is damaged. For example, AST level in serum is elevated in heart attacks or with muscle injury. It is therefore, not a highly specific indicator of liver injury as its elevation can occur as a result of other injured tissues.
ALT (SGPT) is, by contrast, normally found largely in the liver. This is not to say that it is exclusively located in the liver, but that is where it is most concentrated. It is released into the bloodstream as the result of liver injury. Thus, it serves as a fairly specific indicator of liver status.
Normal levels of AST and ALT :
• The normal range of values for AST (SGOT) is about 5 to 40 units per liter of serum (the liquid part of the blood).
• The normal range of values for ALT (SGPT) is about 7 to 56 units per liter
AST and ALT serum levels in some liver conditions can range anywhere from ten times the upper limits of normal to thousands of units/liter. The highest levels of AST and ALT are found with disorders that cause rapid death of numerous liver cells (extensive hepatic necrosis). Although this degree of liver enzymes elevation is not common, it can occur in such conditions as:
• Acute viral hepatitis A or B
• Profound liver damage inflicted by toxins as from an overdose of acetaminophen (brand-name Tylenol) or mushroom poisoning
• Prolonged collapse of the circulatory system (shock) when the liver is deprived of fresh blood providing oxygen and levels can be elevated in biliary conditions (disease of the gallbladder and bile ducts) along with alkaline phosphatase.