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 . 
This paper evaluates the differences between HCA (hepatocellular adenoma) and FNH (focal nodular hyperplasia) and the association of HCA and FNH with OC (oral contraceptives). FNH occurs at least twice as frequent in females as in males. A study conducted by the author revealed that only 20% of patients with FNH had symptoms and signs related to their neoplasms; in the rest, FNH was accidentally discovered during surgery for diseases of the gallbladder or at necropsy. The highly characteristic gross appearance of FNH is discribed in detail. The etiologic relationship between FNH and OC was cited in the light of frequent findings of FNH in infants and children, and of suggestions by other authors that FNH could be a direct result on OC therapy or that contraceptive steroids or conjugated estrogens accelerate the growth of FNH, a very slow growing neoplasm. Simple excision is the treatment of choice for FNH; in some cases, hepatic artery ligation is indicated. In the case of HCA, statistics show that the incidence of HCA has been increasing since 1960. Majority of patients with HCA have normal tests of hepatic function. Radiographic studies and hepatic scans may reveal HCA, but the best diagnostic method so far is angiography. Although gross appearance of HCA is variable, the features are clearly distinguishable from that of FNH. Other topics discussed include the occasional occurence of nodular regenerative hyperplasia in patients on OC or anabolic steroids (AS), and malignant liver tumors in patients using OC or AS. Further research should be done to clarify the etiologic relationship between androgenic-anabolic steroids and hepatocellular tumors and tumorlike lesions.
What's known on the subject? and What does the study add? The negative impact of AAS abuse on male fertility is well known by urologists. The secondary hypogonadotropic hypogonadism is often highlighted when AAS and fertility are being discussed. On the other hand, the patterns of use, mechanisms of action and direct effects over the testicle are usually overseen. The present study reviews the vast formal and "underground" culture of AAS, as well as their overall implications. Specific considerations about their impact on the male reproductive system are made, with special attention to the recent data on direct damage to the testicle. To our knowledge this kind of overview is absolutely unique, offering a distinguished set of information to the day-by-day urologists. For several decades, testosterone and its synthetic derivatives have been used with anabolic and androgenic purposes. Initially, these substances were restricted to professional bodybuilders, becoming gradually more popular among recreational power athletes. Currently, as many as 3 million anabolic-androgenic steroids (AAS) users have been reported in the United States, and considering its increasing prevalence, it has become an issue of major concern. Infertility is defined as the failure to achieve a successful pregnancy after 12 months or more of regular unprotected intercourse, with male factor being present in up to 50% of all infertile couples. Several conditions may be related to male infertility. Substance abuse, including AAS, is commonly associated to transient or persistent impairment on male reproductive function, through different pathways. Herein, a brief overview on AAS, specially oriented to urologists, is offered. Steroids biochemistry, patterns of use, physiological and clinical issues are enlightened. A further review about fertility outcomes among male AAS abusers is also presented, including the classic reports on transient axial inhibition, and the more recent experimental reports on structural and genetic sperm damage.