Steroids are a very large class of compounds which occur in all animals. The steroids used by athletes are mostly androgenic steroids: steroids which act like testosterone. The steroids used to treat inflammatory disorders (e.g. prednisolone, cortisone,beclomethasone, budesonide, dexamethasone and dozens of others) are cortico steroids and do not have anabolic effects.

Testosterone in the male is produced mainly in the testis, a small amount being produced in the adrenal. It is synthesized from cholesterol. The regulation of its production may be simplified thus: the hypothalamus(part of the brain) produces gonadotrophin releasing hormone (GnRH) which acts on the anterior pituitary to increase the production of luteinizing hormone (LH) and follicle stimulating hormone (FSH). LH acts on the Leydig cells in the testis, causing them to produce testosterone. FSH, together with testosterone act on the Sertoli cells in the testis to regulate the production and maturation of spermatozoa. Testosterone in turn acts on thehypothalamus and anterior pituitary to suppress the production of GnRH, FSHand LH, producing a negative-feedback mechanism which keeps everything well-regulated. The small amount produced in the adrenal (in both sexes) is regulated by secretion of adrenal corticotrophic hormone (ACTH), also secreted by the pituitary.

Testosterone, and its metabolites such as dihydrotestosterone, act in many parts of the body, producing the secondary sexual characteristics ofthen male: balding, facial and body hair, deep voice, greater muscle bulk,thicker skin, and genital maturity. At puberty it produces acne, the growth spurt and the enlargement of the penis and testes as well as causing thefusion of the epiphyses (through its conversion to estrogen), bringing growth in height to an end. It plays some role in maintaining the sexualorgans in the adult, but only a low concentration is required for this.

The normal production of testosterone in the adult male is 4 to 9mg per day. The normal plasma concentration is 22.5nmol/l, of which 97% is protein bound. Most is excreted in the urine as 17-keto steroids, but a small amount is converted to oestrogens.

Various analogs of testosterone are used in medical treatment of testicular failure, hereditary angioedema, anemia, severe endometriosis anda few other conditions. Testosterone itself is given by injection. Oral preparations such as methyltestosterone, fluoxymesterone, mesterolone andstanolone are sometimes used, but they cause substantially more liverdamage than injectable or rectally administered preparations because they are absorbed from the gut and transported first to the liver (like most things taken by mouth), where they reach quite high concentrations and are extensively metabolized before circulating to the rest of the body.

Many other analogs have been developed with more anabolic effect than testosterone. These include such famous names as stanozolol, nandrolone,ethyloestrenol and oxymetholone. They all have substantially the same effects as testosterone: retention of sodium, potassium, water, calcium,sulfate, and phosphate, increased muscle synthesis in response to exercise and possible increases in aggression and or libido.

They act on the hypothalamus and pituitary to suppress the productionof GnRH, FSH and LH, causing a virtual cessation in the production of natural testosterone in the testes and also reducing or stopping the production of spermatozoa. This effect does not always reverse when the artificial androgens are stopped.

Cancers of the prostate are frequently dependent on testosterone(hence their treatment by castration) and they may progress very rapidly in the presence of high level of androgens.

A percentage of testosterone is converted to estrogen and some artificial androgens have some estrogen effect as well, causing enlargement of the breast tissue behind the nipple (gynaecomastia). This is occasionally seen naturally in pubescent boys and a small percentage of the adult male population. This effect may be reduced by drugs which inhibit the binding of estrogen to its receptors: e.g.clomiphene, cyclofenil and tamoxifen or drugs that block the enzyme,aromatase, that converts testosterone to estrogen.

So are they safe? The approval and use of any drug is a matter of deciding whether the therapeutic benefits from its use are worth the adverse effects. No drug is safe; acetaminophen (paracetamol) causes some verynasty fatal poisonings, aspirin causes rare cases of devastating skinreactions. Problems occur with every pharmaceutical and it is usually dose dependent. However, the concensus is that they save enough lives and alleviate enough problems to more than compensate for the bad effects. In therapeutic doses, steroids result in few side effects.

Androgenic steroids