Histologic Abnormalities in Children with Nonalcoholic Fatty Liver Disease and Normal or Mildly Elevated Alanine Aminotransferase Levels.

Abstract

Objectives: To investigate the histological spectrum of nonalcoholic fatty liver disease (NAFLD) in children with normal, mildly elevated (26–50 U/L boys, 23–44 U/L girls), or elevated (> 50 boys, > 44 girls) serum alanine aminotransferase (ALT) levels. Study design: The Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) enrolls children 5–18 years with NAFLD. We analyzed baseline clinical and histological data from 91 children with suspected NAFLD and normal or mildly elevated ALT and liver biopsy within 180 days of ALT, and compared them with 392 children with elevated ALT. Results: Of 91 children, 17 (19%) had normal and 74 (81%) had mildly elevated ALT levels. Overall, 45% of biopsies had ≥ 33% steatosis, lobular inflammation grade was ≥ 2 in 22%, 81% had portal inflammation, 29% had ballooned hepatocytes, 35% had “suspicious/borderline” steatohepatitis, and 8% had definite NASH, 34% had NAFLD activity score (NAS) ≥ 4. Overall, 46% had fibrosis (38% mild/moderate and 8% bridging/cirrhosis). Marked steatosis (50% vs 24%) and fibrosis (54% vs 12%) were significantly more common in mildly elevated vs normal, with no difference in ballooning, inflammation, or NAS ≥ 4. Fibrosis stage 3/4 was seen in none of the children with normal ALT, and in 9% of the mildly elevated and 15% of the elevated. Conclusions: Liver biopsies of children with NAFLD with normal or mildly elevated ALT levels show significant histologic abnormalities, including advanced fibrosis in children with mildly elevated ALT. ALT thus may underestimate liver injury in NAFLD. Appropriate ALT cut-off levels can help identify children at risk for more severe disease.