Fibrosis and steatotic liver disease in US adolescents according to the new nomenclature.

objectiveTo apply the new nomenclature for steatotic liver diseases (SLD), replacing nonalcoholic fatty liver disease (NAFLD) with metabolic dysfunction-associated steatotic liver disease (MASLD), in adolescents using National Health and Nutrition Examination Survey (NHANES) data.

methodsAmong 1410 adolescents (12-19 years) in NHANES (2017-March, 2020), the controlled attenuation parameter (CAP) of transient elastography (TE) was used to define steatosis and fibrosis (TE ≥ 7.4 kPa). Obesity and alanine aminotransferase (ALT) ≥ 80 U/L were used to identify adolescents qualifying for hepatology referral according to practice guidelines. NAFLD was defined as liver steatosis without a specific exposure; it has no cardiometabolic risk factor requirement, unlike MASLD.

resultsSteatosis (yes/no) is the first decision point in the new diagnostic protocol; however, criteria for steatosis are undefined. At the supplier (EchoSens)-recommended CAP threshold of 240 dB/m, 30.5% (95% confidence interval [CI]: 27.1%-34.0%) of adolescents had SLD and about 85% of adolescents with NAFLD met criteria for MASLD. The other 15% would receive an ambiguous diagnosis of either cryptogenic SLD or possible MASLD. At higher CAP thresholds, MASLD/NAFLD concordance increased and approached 100%. Among adolescents with MASLD-fibrosis, only 8.8% (95% CI: 0%-19.3%) had overweight/obese and ALT ≥ 80 U/L.

conclusionsThe new nomenclature highlights the high prevalence of liver steatosis. At the CAP threshold of 240 dB/m, however, approximately 15% of adolescents would receive an ambiguous diagnosis, which could lead to confusion and worry. Fewer than 10% of adolescents with MASLD-fibrosis had overweight/obese and ALT ≥ 80 U/L. Revised guidelines are needed to ensure that the other 90% receive appropriate referral and liver disease care.