Autoantibodies Significance in Pediatric Fatty Liver Disease

A Khayat, B Vitola et al. J Pediatr 2021; 239: 155-160. Prevalence and Clinical Significance of Autoantibodies in Children with Overweight and Obesity with Nonalcoholic Fatty Liver Disease

When investigating elevated liver enzymes in teenagers, serology for autoimmune hepatitis (AIH) is frequently obtained. In the face of overweight/obesity, the majority will have nonalcoholic fatty liver disease (NAFL). How many with elevated autoantibodies actually have autoimmune liver disease (ALD)? Some information regarding this issue is available in the article by Khayat et al.

Methods: A retrospective, cross-sectional study of 181 children with a biopsy-proven diagnosis of NAFL, NASH, autoimmune hepatitis (AIH), or primary sclerosing cholangitis (PSC) and a body mass index (BMI) >85th percentile treated between 2007 and 2016.

Key findings:

  • Antinuclear antibody (ANA), anti-actin antibody, and anti–liver kidney microsomal (LKM) antibody were positive in 16.1%, 13.8%, and 0%, respectively, of the patients with NAFL and in 32.8%, 15.5%, and 0%, respectively, of those with NASH
  • Total immunoglobulin G (IgG) was elevated in 27.3% of the patients with NAFL and in 47.7% of those with NASH, but in 100% of those with ALD. A normal IgG level was the “strongest negative predictor of ALD, followed by a negative ANA and actin.”
  • The positive predictive value of LKM was 100% for ALD but only 29% for ANA and 46% for anti-actin antibody. ANA positivity in this cohort was associated with more insulin resistance
  • ALD was present in 29/181 (16%).  12 (6.6%) with isolated ALD (AIH, PSC, or overlap), and 17 (9.4%) with combined ALD and NAFLD
  • BMI >98% “appears to be an important breakpoint above which ALD is less likely” even when IgG is high with a positive ANA
  • Limitations: Retrospective study, not every patient had all of the ALD serology tests

My take: Even heavy kids may have autoimmune liver disease. In those with abnormal serology, about 1 in 6 will have ALD, either in combination with NAFL or as the sole etiology of abnormal LFTs.

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