Diseases of the kidneys are among the most important causes of death and disability in many countries throughout the world. For example, in 2014, more than 10 percent of adults in the United States, or more than 26 million people, were estimated to have chronic kidney disease, and many more millions have acute renal injury or less severe forms of kidney dysfunction.
Severe kidney diseases can be divided into two main categories:
1. Acute kidney injury (AKI), in which there is an abrupt loss of kidney function within a few days; the term acute renal failure is usually reserved for severe acute kidney injury where the kidneys may abruptly stop working entirely or almost entirely, necessitating renal replacement therapy such as dialysis, as discussed later in the chapter. In some instances, patients with AKI may eventually recover nearly normal kidney function.
2. Chronic kidney disease (CKD), in which there is progressive loss of function of more and more nephrons that gradually decreases overall kidney function.
Within these two general categories, there are many specific kidney diseases that can affect the kidney blood vessels, glomeruli, tubules, renal interstitium, and parts of the urinary tract outside the kidney, including the ureters and bladder. In this chapter, we discuss specific physio logic abnormalities that occur in a few of the more important types of kidney diseases.
