Abstract
Background
Despite wide use of serum alanine aminotransferase (ALT) in screening and evaluating liver disease, the definition of a normal ALT is controversial. Here, we aimed to determine the prevalence of steatotic liver disease, metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction and alcohol-associated liver disease (MetALD), and hepatic fibrosis across normal ALT ranges.Methods
We performed a cross-sectional study using the National Health and Nutrition Examination Survey. Adults were stratified based on ALT levels of ≤10, 11-20, 21-30, 31-40, 41-80, and >80 U/L. Vibration-controlled transient elastography was used to assess hepatic steatosis (controlled attenuation parameter of ≥ 285 dB/m), and clinically significant and advanced fibrosis (> 8.6 kPa and 13.1 kPa, respectively). Outcomes included the prevalence of steatotic liver disease, MASLD, MetALD, and hepatic fibrosis across ALT strata. Multivariable logistic regression examined the association between normal ALT strata and each outcome.Results
In 5,245 adults, steatotic liver disease prevalence increased stepwise from 17% at ALT ≤10 U/L to 26% at ALT 11-20 U/L, 44% at 21-30 U/L, and 52% at 31-40 U/L (pConclusion
A significant burden of steatotic liver disease, MASLD, MetALD, and hepatic fibrosis exists at ALT values commonly considered normal, suggesting current reference ranges may be too high to reliably exclude liver disease.