GGT (GAMMA-GLUTAMYL TRANSPEPTIDASE)
GGT is believed to be involved in the transport of amino acids and peptides into cells as well as glutathione metabolism. GGT is mainly found in liver cells and as such is extremely sensitive to alcohol use. Elevated levels may be found in liver disease, alcoholism, bile-duct obstruction, cholangitis, drug abuse, and in some cases excessive magnesium ingestion. Decreased levels can be found in hypothyroidism, hypothalamic malfunction and low levels of magnesium.
Normal Adult Female Range: 0 - 45 U/L Optimal Female:
Normal Adult Male Range: 0 - 65 U/L Optimal Male:
The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine .