Liver Function Test

Liver function tests (LFTs) are a group of blood tests used to assess the function and health of the liver. These tests measure various enzymes, proteins, and substances in the blood that are produced by the liver or released when liver cells are damaged or inflamed. Liver function tests help diagnose liver diseases, monitor liver function, and assess the severity of liver damage. Here are the common components of liver function tests:

1. Alanine Aminotransferase (ALT):
   • ALT is an enzyme found primarily in liver cells. When liver cells are damaged or inflamed, ALT is released into the bloodstream.
   • Normal range: 7-56 U/L (values may vary slightly between laboratories)
   • Elevated ALT levels may indicate liver damage or inflammation, such as hepatitis, fatty liver disease, or liver injury from medications or toxins.
2. Aspartate Aminotransferase (AST):
   • AST is an enzyme found in liver cells, as well as in other organs such as the heart, kidneys, and muscles. Elevated levels of AST in the blood may indicate liver damage, but AST is less specific to the liver than ALT.
   • Normal range: 5-40 U/L (values may vary slightly between laboratories)
   • Elevated AST levels can occur in liver diseases, heart attacks, muscle injuries, and other conditions affecting the liver or other organs.
3. Alkaline Phosphatase (ALP):
   • ALP is an enzyme found in bile ducts, liver cells, bones, and other tissues. Elevated ALP levels may indicate liver or bone disease.
   • Normal range: 44-147 U/L (values may vary slightly between laboratories)
   • Elevated ALP levels can occur in liver diseases, bile duct obstruction, bone disorders (e.g., Paget’s disease, bone metastases), and other conditions.
4. Total Bilirubin:
   • Bilirubin is a waste product produced by the breakdown of hemoglobin in the liver. Elevated bilirubin levels may indicate liver disease, bile duct obstruction, or hemolytic disorders.
   • Normal range: 0.1-1.2 mg/dL (1.7-20.5 μmol/L)
   • Elevated levels of bilirubin can lead to jaundice (yellowing of the skin and eyes) and may be associated with liver diseases such as hepatitis or cirrhosis.
5. Direct Bilirubin:
   • Direct bilirubin (conjugated bilirubin) is a form of bilirubin that has been processed by the liver and is excreted into bile. Elevated levels of direct bilirubin may indicate liver or bile duct disease.
   • Normal range: <0.3 mg/dL (<5.1 μmol/L)
   • Increased direct bilirubin levels can occur in conditions such as bile duct obstruction, cholestasis, or liver diseases affecting bile metabolism.
6. Albumin:
   • Albumin is a protein produced by the liver and helps maintain oncotic pressure in the blood and transport substances such as hormones and drugs.
   • Normal range: 3.5-5.0 g/dL (35-50 g/L)
   • Decreased albumin levels may indicate liver disease, malnutrition, kidney disease, or other conditions affecting protein synthesis.
7. Total Protein:
   • Total protein measures the total amount of protein in the blood, including albumin and globulins.
   • Normal range: 6.0-8.3 g/dL (60-83 g/L)
   • Abnormal total protein levels can occur in liver disease, kidney disease, malnutrition, or other conditions affecting protein metabolism.

These liver function tests are routinely performed in clinical practice to evaluate liver function, diagnose liver diseases, monitor treatment response, and assess the severity of liver damage. Abnormal results may indicate liver dysfunction or disease and may warrant further evaluation and management by a healthcare provider or hepatologist.

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