What causes elevated Alanine Transaminase (ALT) levels from a young age?

From the Guidelines

Elevated Alanine Transaminase (ALT) levels from a young age are most likely caused by Nonalcoholic Fatty Liver Disease (NAFLD), which is a spectrum of fat deposition and hepatic inflammation followed by fibrosis due to metabolic insults, often associated with obesity and insulin resistance.

Causes of Elevated ALT Levels

• Hepatocellular injury causes the release of ALT and AST in serum, and increase in ALT is directly linked to hepatocyte injury 1
• Other causes of rising ALT include acute or chronic viral hepatitis, acute Budd-Chiari syndrome, ischemic hepatitis, autoimmune, hemochromatosis, medications/toxins, autoimmune, alpha1-antitrypsin deficiency, and Wilson disease 1
• NAFLD is the most common liver disease in first world countries, with a prevalence of 20% to 30% in the general population; however, this increases to 70% with obesity and 90% with diabetes mellitus 1 ### Screening for NAFLD
• ALT is used as a screening method for NAFLD in overweight and obese children and adolescents, with a threshold value of 26 IU/L for boys and 22 IU/L for girls 2
• However, ALT alone may underestimate the extent of liver injury, and histological abnormalities in children with NAFLD and normal or mildly elevated ALT levels may show significant histological abnormalities, including advanced fibrosis 3
• Abdominal ultrasound is also recommended as a screening test for NAFLD, especially in children with elevated ALT levels 2

From the Research

Causes of Elevated Alanine Transaminase (ALT) Levels

Elevated ALT levels in young individuals can be caused by various factors, including:

• Infections, with hepatitis A virus (HAV) infection being a leading cause 4
• Drug-induced liver injury (DILI) 4
• Non-alcoholic fatty liver disease (NAFLD) 4, 5, 6, 7, 8
• Alcoholic liver disease 6
• Hereditary hemochromatosis 6
• Alpha1-antitrypsin deficiency 6
• Autoimmune hepatitis 6
• Wilson disease 6
• Thyroid disorders 6
• Celiac sprue 6
• Hemolysis 6
• Muscle disorders 6

Risk Factors Associated with Elevated ALT Levels

Several risk factors are associated with elevated ALT levels, including:

• Obesity 5, 7, 8
• Metabolic syndrome 5, 7
• Insulin resistance 5
• Waist circumference 5
• Fasting insulin level 5
• Ethnicity, with Mexican American adolescents having a higher prevalence of elevated ALT levels compared to white adolescents 5
• Sex, with male adolescents having a higher prevalence of elevated ALT levels compared to female adolescents 5
• Age, with older adolescents having a higher prevalence of elevated ALT levels 8

Prevalence of Elevated ALT Levels

The prevalence of elevated ALT levels varies among different populations, with:

• 7.4% of white adolescents, 11.5% of Mexican American adolescents, and 6.0% of black adolescents having elevated ALT levels 5
• 12.4% of male adolescents and 3.5% of female adolescents having elevated ALT levels 5
• 6% of overweight adolescents and 10% of obese adolescents having elevated ALT levels 8