GPT and End Stage Liver Disease: Nonalcoholic fatty liver disease affects 10 - 24% of the general population in various countries and may progress to end-stage liver disease.[1] Mildly to moderately elevated serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) or both are the most common and often the only laboratory abnormality found in patients with NAFLD.[2]