What Blood Test to Check Fatty Liver? A Complete Guide

For a direct answer: the most common blood test to check for fatty liver disease is a comprehensive metabolic panel (CMP) that includes liver enzymes such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), often paired with gamma-glutamyl transferase (GGT). Today, these markers remain the first-line screening tools for non-alcoholic fatty liver disease (NAFLD) and its more severe form, non-alcoholic steatohepatitis (NASH). However, no single blood test can definitively diagnose fatty liver; a combination of lab results, imaging, and clinical history is essential for accurate assessment.

Understanding Fatty Liver and Its Blood Test Markers

Fatty liver disease occurs when excess fat accumulates in liver cells, affecting up to 30% of adults in the United States. It often shows no symptoms until advanced stages. Blood tests help detect liver inflammation, damage, and fibrosis. The primary markers include:

• ALT (alanine aminotransferase): Elevated levels suggest liver cell injury. Normal range is typically 7-56 U/L, but thresholds vary by lab.
• AST (aspartate aminotransferase): Often elevated alongside ALT. An AST/ALT ratio greater than 0.8 can indicate NAFLD.
• GGT (gamma-glutamyl transferase): A sensitive marker for biliary obstruction and fatty liver, often elevated even when ALT/AST are normal.
• Alkaline phosphatase (ALP): May rise in cholestatic patterns associated with fatty liver.
• Total bilirubin: Usually normal in early fatty liver but can increase with advanced disease.

Secondary Blood Tests for Fatty Liver Evaluation

Fibrosis-4 (FIB-4) Index

This non-invasive score uses age, platelet count, ALT, and AST to estimate liver fibrosis risk. A FIB-4 below 1.3 suggests low risk, while above 2.67 indicates advanced fibrosis, guiding the need for further testing.

NAFLD Fibrosis Score (NFS)

Combines age, BMI, impaired fasting glucose, AST/ALT ratio, platelet count, and albumin. It helps differentiate simple steatosis from NASH with fibrosis.

Enhanced Liver Fibrosis (ELF) Test

Measures three serum markers: hyaluronic acid, procollagen III N-terminal peptide, and tissue inhibitor of metalloproteinase 1. ELF is increasingly used today for staging fibrosis without a biopsy.

Comparison of Common Blood Tests for Fatty Liver

When to Order These Tests

Your healthcare provider may recommend a fatty liver blood panel if you have risk factors: obesity, type 2 diabetes, high triglycerides, metabolic syndrome, or a family history of liver disease. Today, updated guidelines from the American Association for the Study of Liver Diseases (AASLD) suggest screening adults over 40 with these risk factors using ALT and FIB-4. If results are abnormal, imaging such as ultrasound, elastography (FibroScan), or MRI-PDFF is often ordered to confirm fat content and fibrosis.

Limitations and Next Steps

Blood tests alone cannot quantify liver fat or distinguish simple steatosis from NASH. For example, up to 30% of patients with NAFLD have normal ALT levels. Therefore, a negative blood test does not rule out fatty liver. If you have persistent symptoms like fatigue, right-upper-quadrant pain, or unexplained elevated liver enzymes, follow-up with a specialist is critical. Lifestyle changes—weight loss, reduced sugar intake, and exercise—remain the cornerstone of management.

Get Tested with Any Lab Test Now

Take control of your liver health today. Any Lab Test Now offers comprehensive fatty liver blood panels, including CMP, GGT, and fibrosis scores, without a doctor’s referral. Results are typically available within 24-48 hours. Order your fatty liver blood test now and receive a secure, physician-reviewed report you can share with your doctor.