Dialysis is a medical blood purification procedure that is used when the kidneys can no longer adequately perform their vital functions. Normally, the kidneys filter the blood: they remove waste products (e.g., urea, creatinine) and excess water, regulate blood pressure and salt and acid balance, and produce vital hormones (e.g., vitamin D, renin). The loss of these functions leads over time to the accumulation of toxins in the body, which can cause edema, anemia, osteoporosis, and ultimately life-threatening complications such as cardiovascular failure. Dialysis can avert this danger to life.