RESUMO
Glucocorticoids (GCs) are among the most commonly used drugs. They have been employed to treat almost every known disease, from urticaria to leukemia. GCs are so termed because of their action to increase plasma glucose as a result of enhanced hepatic gluconeogenesis, but they play, also, key regulatory roles in a wide variety of physiologic processes. They are essential for survival under stress. GC effect is mediated through receptors localised in cytosol. Receptor-GC complexes bind to hormone response elements in nuclear DNA, affect transcription of genes, either stimulating or inhibiting mRNAs. Proteins so produced (enzymes, hormones) are responsible for the steroid response. There is one type of GC receptor and all GCs will affect all tissues in the same way. At present rational use of GCs falls into two categories: replacement therapy (in Addison's diseasse and in congenital adrenal hyperplasia) and pharmacotherapy, mostly for their anti-inflammatory and immunosuppressive properties, but also to lyse leukemic lymphocytes or to reduce brain edema. GC therapy does not cure the primary disease--it only ameliorates its manifestations and provides time for the body natural defenses to work. After the withdrawal of steroid therapy manifestations of primary process usually return. So, as a result, there is no positive effect on long-term prognosis. Most common indications for prologned high-dose GC therapy are in organ transplantation, tumour chemotherapy, collagen vascular syndromes, ulcerative colitis, nephrotic syndrome and regional enteritis. Asthma, allergic diseases, inflammatory eye diseases and blood dyscrasias are also often treated with GCs. Used in pharmacological doses GCs have a number of adverse side effects. The use of alternate 0 day therapy can decrease most GC side effects (less suppression of hypothalamic-pituitary-adrenal axis, growth inhibition, cushingoid features, infections and myopathy). Discontinuation of long-term therapy is potentially difficult ("steroid withdrawal syndrome"). It is necessary to reduce the total dose gradually, in small weekly decrements. Recent use of GCs in prenatal treatment of congenital adrenal hyperplasia is described.