AST (aspartate aminotransferase) and ALT (alanine aminotransferase) are enzymes that indicate liver cell damage when elevated. While injectable testosterone is not particularly hepatotoxic (unlike oral 17-alpha-alkylated steroids), liver function should still be monitored on TRT. Oral ancillary medications like anastrozole and enclomiphene are processed by the liver.
Additionally, metabolic changes from TRT (improved body composition, reduced fatty liver) can actually improve liver enzymes in men with baseline non-alcoholic fatty liver disease.