Cholesterol - Cholesterol is a major precursor of cholesterol ester, bile acids, and steroid hormones and is a component of plasma membranes. It is a necessary component of all cell membranes. It is the precursor to all steroid hormone (including estrogen , testosterone , cortisol , and vitamin D ). It is the leading organic molecule in the brain and is needed for brain function. However, too much cholesterol in the bloodstream can be unhealthy, it builds up in the artery wall and can lead to the signs and symptoms of coronary heart disease.
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 .