The enzyme ALT is unique to hepatocellular injury since it is mostly concentrated in hepatocytes, with smaller quantities in cardiac, renal, and muscular tissue.  ALT levels frequently change during the day.  Energy generation depends on the hepatocyte's ability to produce glutamate and pyruvate, which is facilitated by ALT .  Male ALT typically ranges from 29 to 33 IU/L, while female ALT typically ranges from 19 to 25 IU/L . 
The hepatobiliary tract, bone, placenta, and intestinal tissue are the main locations for the enzyme ALP.  ALP participates in several dephosphorylating processes.  ALP typically ranges from 30 to 120 IU/L.  Because of the higher osteoblastic activity linked to bone formation, ALP is often higher in children and teenagers. 
The enzyme 5'nucleotidase is found in numerous tissues, although its therapeutic utility is most important in cholestatic or hepatobiliary disorders.  It is typically employed as a test to assist in determining whether an isolated high ALP originates from an osseous or hepatobiliary source.  Its main use is in reactions involving nucleotide hydrolysis.  The typical range for 5'nucleotidase is 0.3–3.2 Bodansky units; higher serum ALP is required to correct levels. 
Like ALT, AST is an enzyme that is also found in the liver, but it is also present in other places where it is less common than ALT.  Skeletal muscle, heart muscle, kidney tissue, and the brain are the main locations for these.  It manifests as two isoenzymes with minimal clinical utility that cannot be distinguished by conventional testing.  Amino acid metabolism is aided by AST.  Because it is present in various tissues, care must be used while assessing abnormal AST levels.  AST often ranges below 35 IU/L. 
The enzyme GGT is present in the liver, kidneys, biliary tract, seminal vesicles, and pancreas, among other organs.  In conjunction with an increase in other liver biochemical tests, its elevation is typically regarded as important for a hepatobiliary illness.  It is typically higher in cytochrome-inducing drugs, alcohol addiction, and biliary diseases.  GGT plays a role in the generation and metabolism of glutathione in a number of bodily tissues.  The normal range for GGT is 0–30 IU/L.  Infants typically have GGT levels 6–8 times greater [9]. A common enzyme in the body, LDH has several isoenzymes, one of which is mainly eliminated or absorbed by the liver's Kupffer cells.  Elevated LDH can therefore be a result of liver disease or injury.  This is a non-specific method that is rarely used to assess liver disease.  140–280 U/L is the normal range for LDH (ranges vary somewhat between labs).