The liver is a large, vital organ that performs many critical functions for maintaining health and sustaining life. It is located in the upper right part of the abdomen, just below the right side of the chest, extending into the central position of the abdomen. To understand what liver function tests are and why they are performed, you first need to know more about liver function. Important functions of the liver The liver is a complex organ that: Produces proteins, including blood clotting factors and albumin Synthesizes, stores, and metabolizes fats, fatty acids, and cholesterol Metabolizes carbohydrates and stores them for energy Forms and secretes bile , which contains bile acids necessary for the absorption of fats and vitamins. Metabolizes, secretes and eliminates harmful end products produced by normal bodily processes, including bilirubin and ammonia. Metabolizes, secretes and detoxifies environmental toxins, drugs and alcohol introduced into the body. The liver, thus, it helps in many bodily functions, such as digestion, excretion, providing energy to the body, protecting the body from bleeding to death and more. When one or more of these functions is disrupted by illness or injury, symptoms may not appear immediately due to the large liver reserve that protects and restores its function. Significant damage, which can occur over time, is usually required before symptoms appear. Symptoms of liver disease When liver function is impaired by disease or injury, these symptoms may occur: Yellowing of the skin and the whites (sclerae) of the eyes – due to the liver's inability to metabolize and secrete bilirubin, which has a yellow pigment Easy bruising or bleeding – due to the liver's inability to produce enough blood clots...... center of paper ......zyme present in many tissues including the liver. Although nonspecific, increased LD levels may suggest liver damage. Prothrombin time or PT. This test checks the amount of time it takes for blood to form a clot. If it is higher than normal, it could indicate that there are low levels of blood clotting factors, which could be due to liver disease. PT can be performed in conjunction with PTT (partial thromboplastin time) and INR (international normalized ratio), which are not strictly liver function tests, but are standard methods for laboratories to report PT.Works CitedMedicineNet. Liver. http://www.onhealth.com/liver/page2.htm#what_is_the_function_of_the_liver.Mayo Clinic. Liver function tests. http://www.mayoclinic.org/tests-procedures/liver-function-tests/basics/why-its-done/prc-20012602WebMD. Liver function tests. http://www.webmd.com/a-to-z-guides/liver-function-test-lft