Liver function tests (LFTs) are a group of blood tests used to assess the health and function of the liver. These tests measure various enzymes, proteins, and other substances in the blood that are indicative of liver function. LFTs are essential in diagnosing liver diseases, monitoring treatment effectiveness, and evaluating overall liver health.
Parameters Assessed: | |
Alanine Aminotransferase (ALT): | ALT is an enzyme found primarily in the liver. Elevated levels of ALT in the blood indicate liver damage or inflammation. |
Aspartate Aminotransferase (AST): | AST is an enzyme present in the liver, heart, muscles, and other organs. Elevated AST levels may indicate liver damage, but they can also be elevated in conditions affecting other organs. |
Alkaline Phosphatase (ALP): | ALP is an enzyme found in various tissues, including the liver, bones, and bile ducts. Elevated ALP levels may indicate liver or bone disorders. |
Total Bilirubin: | Bilirubin is a yellow pigment produced when the liver breaks down old red blood cells. Elevated bilirubin levels may indicate liver dysfunction or obstruction of the bile ducts. |
Albumin: | Albumin is a protein produced by the liver. Low albumin levels may indicate liver disease or malnutrition. |
Total Protein: | Total protein measures the total amount of protein in the blood, including albumin and other proteins produced by the liver. |
Role of LFT:
1. Metabolism:
The liver is central to metabolism, as it processes and metabolizes nutrients, including carbohydrates, fats, and proteins, obtained from food. LFTs evaluate the liver's ability to metabolize these nutrients efficiently.
2. Detoxification:
One of the liver's primary functions is detoxification, where it filters and removes toxins, drugs, and metabolic waste products from the bloodstream. LFTs help assess the liver's detoxification capacity by measuring enzyme levels involved in these processes.
3. Protein Synthesis:
The liver synthesizes various proteins, including albumin, clotting factors, and transport proteins, essential for maintaining fluid balance, blood clotting, and transportation of nutrients and hormones. LFTs measure protein levels to evaluate the liver's synthetic function.
4. Bile Production and Secretion:
The liver produces bile, a digestive fluid that aids in the digestion and absorption of fats and fat-soluble vitamins in the intestines. LFTs assess the liver's ability to produce and secrete bile by measuring enzymes and substances involved in bile metabolism.
5. Storage:
The liver stores essential nutrients such as glycogen (for energy), vitamins (e.g., vitamins A, B12, and D), and minerals (e.g., iron, and copper). LFTs help evaluate liver health by monitoring levels of stored nutrients and their utilization.
6. Immune Function:
The liver plays a vital role in immune function by filtering pathogens and foreign particles from the bloodstream and producing immune factors that help fight infection. LFTs can indirectly reflect the liver's immune function by assessing its overall health and integrity.
7. Bilirubin Metabolism:
Bilirubin, a yellow pigment produced from the breakdown of old red blood cells, is metabolized and excreted by the liver. Abnormal bilirubin levels, as detected by LFTs, can indicate liver dysfunction or obstruction of the bile ducts.
8. Monitoring Liver Diseases:
LFTs are essential diagnostic tools in detecting and monitoring liver diseases such as hepatitis, cirrhosis, fatty liver disease, and liver tumours. Abnormal enzyme levels or protein concentrations in LFTs can indicate liver damage, inflammation, or impaired function.
In summary, liver function tests provide valuable insights into the overall health and function of the liver, enabling early detection, diagnosis, and monitoring of liver diseases and disorders. By assessing various biochemical parameters, LFTs help healthcare providers evaluate liver function comprehensively and guide appropriate management and treatment strategies for optimal patient care.
Low and High Values: | |
Low Values: Low levels of albumin and total protein may indicate liver disease, malnutrition, or impaired liver function. | High Values: Elevated levels of ALT, AST, ALP, and bilirubin may indicate liver damage, inflammation, or obstruction of the bile ducts. |
Medical Conditions Associated with Abnormal Values: | |
Elevated ALT and AST: | Hepatitis, liver cirrhosis, fatty liver disease, liver tumours. |
Elevated ALP: | Liver diseases (e.g., cholestasis, liver cancer), bone disorders (e.g., osteoporosis, Paget's disease). |
Elevated Bilirubin: | Jaundice, liver dysfunction, bile duct obstruction. |
Low Albumin and Total Protein: | Liver disease, malnutrition, kidney disease. |
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