How’s your liver behaving?
For the second edition of our series about common tests with Prof. Shyam Fernando, a Consultant Physician and Professor in Medicine, we shift focus to Liver Function Tests (LFTs). These are a collection of blood tests which are done to verify whether your liver is functioning as it should or if it is damaged.
Prof. Fernando explains that the liver, which is in the right side of the upper part of the abdomen, just below the rib cage, is like a processing and manufacturing factory in the body. It detoxifies harmful substances, processes certain nutrients, and manufactures proteins such as those required for blood clotting. It also produces bile which is needed for fat digestion. With so many functions, you need more than one test to check up on it. Here’s what you need to know about LFTs:
What it is:
When the liver is damaged, the enzymes that are contained within the liver cells, leak out. This is checked by doing three tests: ALT (also called SGPT), AST (or SGOT) and ALP. (The full names are long, and difficult to pronounce: alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP)). The manufacturing function of the liver is tested by measuring a protein called albumin in blood.
Bilirubin is another substance produced in the liver that is measured as part of LFTs. Bilirubin is a by-product that is formed when red blood cells reach the end of their life span. Production of clotting factors by the liver is determined by checking the efficiency of blood clotting (PT or Prothrombin time).
How it is it done:
LFTs are done on a sample of blood taken through a prick on an arm vein.
How is it used in diagnosis?
You may be asked to do LFTs as a part of routine health check. They are also done when liver diseases like hepatitis are suspected and in those who take alcohol excessively. In patients taking certain medications that might have harmful ‘liver-side effects’, LFTs are checked periodically.
High levels of liver enzymes (eg. ALT) indicates damage to liver cells. Examples are hepatitis, cirrhosis and excessive alcohol intake. In overweight people, when fat is deposited in the liver, cells get damaged and ALT level might go up. ALTs are also used to check the effect on the liver in patients taking ‘cholesterol pills’ (statins). If the bile duct gets blocked, for example, by a stone, the level of bilirubin in blood will rise as a consequence. These patients are often jaundiced. LFT is also a key test that is done if spread of cancers to the liver is suspected.
How do I prepare?
No special preparations such as fasting are necessary.
What are the after-effects?
None
What are the pitfalls?
Just like any other test, the reports should be read along with other information about the illness obtained from the patient. Don’t be upset if all your numbers don’t fall exactly within the ‘normal range’ given on the report. Slight deviations are not unusual. Only your doctor will know whether you need to take note of that.