According to the Asia-Pacific Working Party, the prevalence of NAFLD in children and adolescents widely differs, based on epidemiologic studies. Assessment of liver ultrasonography showed that the prevalence of NAFLD among Japanese children aged 4-12 years was 2.6%. Whereas, the incidence was found to be 2.1% among 6‐ to 12‐year-olds in Shanghai, China. Meanwhile, 22.8% of obese Taiwanese children and adolescents were diagnosed with ultrasound‐defined NAFLD. However, liver ultrasonography is relatively insensitive for detecting cases with hepatic fat content below 30%.

Serum alanine transferase (ALT) is frequently used to assess the NAFLD prevalence. The Korean National Health and Nutrition Examination Survey 1998, projected that the prevalence of elevated ALT levels (>40 U/L) was 8% in 1 594 adolescents aged 10-19 years. On the other hand, Japan reported a prevalence of ALT >35 U/L 24.1%, among obese children aged 6-15 years.

Limitations of this screening method is that the upper limit of normal ALT is not well established and ALT levels do not indicate the histological severity of NAFLD in children or adults.

Source: Wong VW, Chan WK, Chitturi S, Chawla Y, Dan YY, Duseja A, Fan J, Goh KL, Hamaguchi M, Hashimoto E, Kim SU. Asia-Pacific Working Party on Non‐alcoholic Fatty Liver Disease guidelines 2017—part 1: definition, risk factors and assessment. Journal of Gastroenterology and Hepatology. 2018;33(1):70-85.