Blood Test to Check Fatty Liver: Key Markers

The most effective blood test to check fatty liver is a liver function panel that includes ALT, AST, GGT, and specific biomarkers for nonalcoholic fatty liver disease (NAFLD) such as the NAFLD Fibrosis Score or FIB-4 index. Today, updated guidelines emphasize combining these tests with imaging for accurate staging. Early detection through blood work can prevent progression to cirrhosis, and at-home blood test options are now widely available through services like AnyLabTestNow.

Understanding Fatty Liver and Why Blood Tests Matter

What Is Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) affects about one in three adults in the United States. It occurs when excess fat accumulates in liver cells, often without obvious symptoms. Left undiagnosed, NAFLD can progress to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Blood tests serve as the first line of screening because they are non-invasive, cost-effective, and can be ordered directly by patients through anylabtests.com.

Why Use Blood Tests Instead of Imaging Alone?

While ultrasound and FibroScan are valuable, blood tests provide a baseline of enzyme levels and liver function. They allow for risk stratification using the NAFLD Fibrosis Score or FIB-4, which combine age, ALT, AST, and platelet count. Today, new serum biomarkers like cytokeratin-18 fragments and FGF-21 are gaining traction for early detection.

Top Blood Tests for Fatty Liver Diagnosis

Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST)

ALT is the most specific marker for liver inflammation. An elevated ALT (above 30 U/L in men, 19 U/L in women) suggests fat-related injury. AST can be elevated as well, and the ALT/AST ratio helps differentiate NAFLD from alcoholic liver disease. A ratio less than 1.0 is common in NAFLD.

Gamma-Glutamyl Transferase (GGT)

GGT rises with bile duct stress and is often elevated in NAFLD. It is a sensitive marker even when ALT is normal. Today, GGT is increasingly used alongside ALT in comprehensive panels.

NAFLD Fibrosis Score and FIB-4 Index

These composite scores use routine blood work (ALT, AST, platelets, albumin) and age to estimate fibrosis risk. A FIB-4 below 1.3 rules out advanced fibrosis, while above 2.67 suggests significant scarring. They are endorsed by the American Association for the Study of Liver Diseases (AASLD) for risk stratification without biopsy.

Blood Markers to Assess Liver Health (Updates)

• Complete Blood Count (CBC) – platelet count decreases with fibrosis.
• Liver Panel – includes ALT, AST, GGT, alkaline phosphatase, bilirubin.
• Lipid Panel – NAFLD often accompanies high triglycerides and low HDL.
• Hemoglobin A1c – insulin resistance drives NAFLD progression.
• Ferritin – elevated in NASH and can indicate iron overload.
• Cytokeratin-18 (CK-18) – emerging marker for NASH.

Comparison of Common Blood Tests for Fatty Liver

When to Order a Blood Test for Fatty Liver

If you have risk factors like obesity, type 2 diabetes, high cholesterol, or a family history of fatty liver, a blood test is recommended annually starting at age 40. Even if you feel fine, early detection can reverse steatosis through lifestyle changes. Today, direct-to-consumer labs allow you to order the specific panel your doctor recommends without a visit.

To take control of your liver health today, order our comprehensive Fatty Liver Health Panel at anylabtests.com/go/liver-panel. The panel includes ALT, AST, GGT, FIB-4 calculation, and a lipid profile—everything you need for a current assessment. Results are reviewed by a physician, and you can share them with your healthcare provider.