There is no simple test for non-alcoholic fatty liver disease (NAFLD). Lab tests that show elevated liver enzymes (ALT and AST) may lead to further testing that reveals fatty liver disease, but some people  with NAFLD have normal liver enzymes. Other blood biomarkers may also suggest fatty liver disease.

Clinical signs and reported symptoms tend to be more evident when NAFLD has progressed to non-alcoholic steatohepatitis (NASH)

Various imaging methods can show the presence of fat in the liver. Transient elastography (FibroScan), a type of ultrasound imaging, can reveal both fat accumulation and fibrosis ( buildup of scar tissue in the liver).

A liver biopsy, in which a small sample of liver tissue is collected with a hollow needle and examined under a microscope, is considered the gold standard for diagnosing fatty liver disease. Biopsies can reveal fat in liver cells, fibrosis, inflammation and other liver damage. But this is an invasive test with a small risk of complications, and it is not suitable for routine screening.

Clinicians use a variety of methods to assess the likelihood of fatty liver disease and fibrosis based on combinations of blood biomarkers and demographic factors such as age. The development of more accurate noninvasive methods for diagnosing and monitoring fatty liver disease is an active area of research. 

Last Reviewed: January 27, 2023