The liver is a vital organ in the human body. It has so many functions that we cannot live without it. The funtions of the liver include the following functions: Proteins metabolism and carbohydrate metabolism and in particular glucose metabolism which is called glycolysis. Glycolysis is important along with oxidative phosphorylation( a process which genarates energy in the form of ATP) to generate energy for tissues of the body. Glucose is especially important as energy for the brain cells. Lipid metabolism which is also used to produce energy is also done in the liver. Amino acids synthesis which are building blocks of proteins are synthesized in the liver. these amino acids are called non-essential amino acids because the liver can synthesize them. There are also essential amino acids. These are amino acids that the liver do not synthesize. Our body must have these essential amino acids in the diet in the form of food rich in proteins such as meat. The liver produces essential proteins that are required in maintaining osmotic pressure of body fluids. The most important of these proteins is Abumin. Its deficiency is an indication of liver dysfunction. Its lack also causes edema or accumulation of fluids in the extracellular space. The liver has an important function to produce coagulation factors which contribute to hemostasis. These coagulation factors are proteins which are activated one after the other. In the case of liver dysfuntion, One expects then bleeding to occur easily due to the shortage in clotting factor. A hormone called thrombopoietin is synthesized in the liver and is responsible for stimulating the synthesis of platelets. This hormone deficiency is another indication to liver dysfuntion which is manifested clinically also by bleeding. Another function of the liver is bile synthesis and secretion. In liver disease the synthesis of bile is diminished. The bile is important for digestion of food in the intestine. After its synthesis bile is transported through canals to the gall bladder where it is stored. We see from the previous discussion the importance of the liver through its diversity in function. If any of these functions is disrupted it is manifested as a pathology of the liver. The liver disease can be diagnosed in the clinical laboratory through many markers ( compounds that are tested in the lab and which their excess or deficiency is indicative of liver pathology). Currently, In the clinical laboratory there are several markers (enzymes) which help in diagnosing the pathology of liver. The amino-transferase are one group of markers. They are alanine amino transferse ALT and aspartate amino transferase AST. These markers are sensitive but not specific. The increase in concentration of these two enzymes reflect damage to liver cells such as hepatitis. Alkaline phosphatase ALP is another marker that s used. This marker is sensitive to damage to cells lining the gall bladder ducts. This happens normally due to blockage of one of these ducts from a cholesterol stone. This marker is found also in bones and therfor it is not specific to liver pathology. It has however isoenzymes which can difAnother marker is gamma-glutamyl transferse. This enzyme like ALP is increased in the case of bile canal blockage or cholestasis. A marker for liver cancer is called alfa feto protein. The increase in concentration of this enzyme can be indicative of liver cancer. However, this marker is not specific as it is also increased in germ cells tumors. Prothrombin time is a a measure of function of the coagulation factors synthesized in the liver. A long prothrombin time is indicative of dysfunction of the liver. The last marker that we discuss here is levels of bilirubin in the blood. Bilirubin in derived from hemoglobin degradation of red blood cells. Accumulation of bilirubin in the blood causes jaundice. The accumulation of bilirubin in blood is not specific to liver dysfuntion or bile canal blockage as this condition can occur as a result of hemolysis of red blood cells.ferentiate between the various diseases