Prevention of renal disease and conservation of renal function. In summary, we have reviewed some of the most frequently encountered areas of prevention of renal failure in the elderly. They include obstruction, hypertension, drug interaction, and inappropriate use of drugs and the silent killer of the elderly, renal carcinoma. Only by a thorough understanding of the altered physiology of the aging kidney can the physician avoid making the same mistakes when new drugs are developed or new types of diseases are encountered. Proper early diagnosis and understanding the guidelines to therapy in these conditions, can save huge human costs in terms of mortality, morbidity, and money. 