Liver fibrosis occurs when chronic inflammation leads to scar tissue building up in the liver. Over time these scars can disrupt normal blood flow and impair the organ’s ability to remove toxins from the body. Detecting fibrosis early allows for lifestyle changes or medications that may slow progression to cirrhosis.
The FIB-4 index is a widely used noninvasive formula for estimating fibrosis in patients with hepatitis or other liver diseases. It relies on common blood tests—age, AST, ALT, and platelet count. The equation is . Scores below 1.45 typically indicate minimal fibrosis, while results above 3.25 suggest advanced fibrosis.
Enter your age in years, AST and ALT in units per liter, and platelet count in billions per liter (10^9/L). The output will display the calculated FIB-4 score along with an interpretation—low, intermediate, or high risk of significant scarring. Use recent lab values for the most accurate result.
Platelets play a crucial role in blood clotting. In many liver conditions, platelet counts drop as scarring interferes with normal production and spleen function. Including platelet count in the FIB-4 formula helps differentiate between temporary liver enzyme elevations and more serious chronic injury.
The FIB-4 index is a screening tool. It cannot definitively diagnose fibrosis or replace a liver biopsy when needed. Factors such as acute illness or heavy alcohol consumption can temporarily alter AST or ALT levels and skew the calculation. Always discuss results with a healthcare professional.
Monitoring liver health is vital for individuals with hepatitis B or C, fatty liver disease, or long-term medication use that may strain the liver. Combining FIB-4 with imaging tests and other scores like APRI or FibroScan offers a more complete picture. Early lifestyle changes such as reducing alcohol intake and managing weight can slow fibrosis progression.
Suppose you are 55 years old with an AST of 80 U/L, ALT of 70 U/L, and platelet count of 150. Plugging these into the formula yields , producing a FIB‑4 score of about 1.8. This falls in the gray zone—neither clearly high nor low—so further evaluation might be recommended.
Detecting liver fibrosis early helps you work with a medical professional to prevent complications. Use this calculator as a starting point for conversation with your doctor, and continue regular monitoring if you are at risk.
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