The liver, located in the right upper portion of the abdominal cavity just beneath the right side of the rib cage, has many vital functions. Briefly, some of these functions are:

  • Detoxification of blood
  • Production of important clotting factor and other important proteins
  • Metabolizing (processing) medications and nutrients
  • Processing of waste products of hemoglobin
  • Storing of vitamins, fat, cholesterol, and bile
  • Production of glucose

In general, liver blood tests are used to detect an injury or an inflammation to the liver. These tests are commonly ordered and performed in many situations, such as in routine health screening, evaluation of abdominal pain, or suspected liver disease. The liver blood tests are typically done as a part of the comprehensive metabolic panel which also includes electrolyte levels and kidney function.

Liver blood tests are some of the most commonly performed blood tests. These tests can assess liver functions or liver injury. An initial step in detecting liver damage is a simple blood test to determine the presence of certain liver enzymes (proteins) in the blood.

Under normal circumstances, these enzymes 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 (catalyze) routine and necessary 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 contained within liver cells. If the liver is injured or damaged, the liver cells spill these enzymes into the blood, raising the enzyme levels in the blood and signaling liver disease.

The main values measured in liver blood tests are the aminotransferases (alanine aminotransferase or ALT and aspirate aminotransferase or AST). The other measurements include alkaline phosphate, albumin, and bilirubin. It is important to note that these tests are commonly referred to as “liver function tests”, but this term is misleading as the aminotransferases and alkaline phosphatase do not reflect the function of the liver. Strictly speaking, the true liver function tests (LFT’s) include albumin, bilirubin, blood coagulation panel, and glucose.

More specifically, AST, ALT, and alkaline phosphatase are called the liver enzymes and they typically are used to detect damage or injury to the liver (not its function)

AST (SGOT) is normally found in a variety of tissues including liver, heart, muscle, kidney, and brain. It is released into the serum when any one of these tissues is damaged. For example, its level in serum rises in heart attacks or with muscle disorders. It is therefore, not a highly specific indicator of liver injury as it can occur from 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 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.

Abnormal liver tests may be detected in the blood in a variety of liver conditions:

  • Mild to moderate elevations of the liver enzymes are common.
  • Chronic hepatitis B and hepatitis C is a cause of chronic mild to moderate liver enzyme elevations.
  • Chronic and acute alcohol use is also a common cause of abnormal liver tests.
  • Some medications can cause mild to moderate increase in the liver enzymes.

Hepatitis causes inflammation of the lever. Many conditions can cause inflammation of the liver like drugs, alcohol, chemicals and various autoimmune diseases. Differant viruses like mononucleosis and cytomegalovirus can cause inflammation of the liver. Viruses do not attack the liver and the liver is one of the organs that can be affected by viruses. There are several viruses which cause hepatitis and they are: A,B,C,D,E ,F and G. The most common hepatitis viruses are types A,B and C.

The liver is located in the upper right hand side of the abdominal region mostly behind the rib cage. The weight of liver is normally three pounds. When doctors inform about viral hepatitis then they are talking about attack caused due to viruses on the liver.

The functions of the liver are:

  • The liver helps in purification of blood by changing harmful chemicals into harmless one. The source of these chemicals can be external such as medications or alcohol can be one of major reasons or internal caused by ammonia or bilirubin. These harmful chemicals are made into smaller chemicals and are finally removed from the body in the form of stool or urine.
  • The liver stores many fats, vitamins and sugars until they are needed somewhere else in the body.
  • Manufacture of cholesterol requires liver very much. The liver builds small chemicals into larger and more complicated ones required somewhere in the body. But when the liver is inflamed then it does not perform these functions well which brings about many symptoms and problems related with hepatitis.

Symptoms of Viral Hepatitis

Many patients having hepatitis A, B and C have less or no symptoms or signs of illness. The period between occurrence of hepatitis and the onset of illness is called incubation period. It varies depending on the particular hepatitis virus.

Various signs are:

  • Nausea and vomiting
  • Loss of appetite
  • Weakness and tiredness
  • Fever
  • Ache in abdomen region
  • Light colored stools
  • Dark urine
  • Jaundice and fever

Liver disease is also called as hepatic disease. The disturbance of liver function that causes ailments is called as liver disease. The loss of those functions can cause severe damage to the parts of the body .But as you know the liver is responsible for many critical functions required for body to work and if the body becomes diseased or injured then it can cause harm to the body.

More than 75% of liver tissues get affected before decrease in function occurs. The liver makes and secretes bile and is the biggest organ in the body and is called a gland because of its secretion nature. The liver is made up of two lobes which consist of tiny lobules. It is protected by the rib cage and is located in the upper right part of the abdominal region. The cells of liver has two different sources of blood supply .one is hepatic artery that supplies rich blood containing oxygen that is pumped from the heart while the portal vein supplies nutrients from the spleen and intestine.

The portal vein also sends the chemicals and proteins that cell of liver needs in the production of proteins, cholesterol and glycogen necessary for normal activities of body. The veins return blood from the heart but the portal veins allows chemicals from digestive system to enter the liver for detoxification and filtration is also done before making entrance for general circulation.

The many functions of liver are:

  • The liver secretes bile juice that is required in the digestion of food specially fats.
  • It helps in blood clotting.
  • Extra glucose in the body is converted into glycogen and is stored in liver and gets converted into glucose when the need of the body arises.
  • It is used to produce amino acids which are the building blocks for making proteins including those used to fight infection in the body.
  • The storage and processing of iron required for production of red blood cells (RBCs).
  • The liver manufactures cholesterol and chemicals necessary for transportation of fat.

Hemoglobin which is sometimes abbreviated as Hb or Hgb, is the iron-containing oxygen-transport component of the Red Blood Cells or RBCs of all vertebrates. Hemoglobin a type of metalloprotein carries oxygen from the respiratory organs (lungs) to the rest of the body (i.e., the tissues) where it releases the oxygen. This oxygen is then used to burn nutrients to provide energy to power the functions of the organism. Later it collects the resultant carbon dioxide to bring it back to the respiratory organs to be released out from the organism.

Functions of Hemoglobin

  • Carry oxygen
  • Carry Carbon Dioxide
  • Carry Nitric Oxide

Hemoglobin has an oxygen binding capacity and on average hemoglobin molecule can bind (carry) up to four oxygen molecules. Sometimes Hemoglobin is involved in the transport of other gases: it carries some of the body’s respiratory carbon dioxide as carbaminohemoglobin, in which CO2 is bound to the globin protein. The molecule also carries the important regulatory molecule nitric oxide bound to a globin protein thiol group, releasing it at the same time as oxygen.

Structure of Hemoglobin

  • Hemoglobin is made of protein
  • Protein is made of amino acid or polypeptide
  • Polypeptide sequence depends on DNA

Hemoglobin is primarily made of protein or the “globin” chain. These proteins are folded chains of a large number of different amino acids called polypeptides. The sequence of this polypeptide is determined by the stretches of DNA called genes.

Mutations of hemoglobin

  • Sickle Cell diseases
  • Thalassemias

Mutations in the genes for the hemoglobin protein may result in hemoglobin variants, however many of these mutant forms of hemoglobin cause no disease. But some of these mutant forms of hemoglobin do result in a group of hereditary diseases termed the hemoglobinopathies. The best known hemoglobinopathy is sickle-cell disease, which was the first human disease whose mechanism was understood at the molecular level. Another set of disease called thalassemia is also a result of underproduction of normal and sometimes abnormal hemoglobins. All these diseases produce anemia.