(HealthDayNews) -- If you're lucky, you were born with two functioning kidneys. Between them, they process around 200 quarts of blood daily. In metric terms, that's around 189.3 liters.
Adults normally have a blood volume of about five to six liters (5.3-6.3 quarts). That entire volume is pumped through the fist-sized kidneys roughly 35 times a day. Of that total volume, roughly one percent (2 quarts, or 1.9 liters), is waste that is converted by the kidneys into urine.
That waste is filtered out by a million tiny blood vessel-units called nephrons, which also measure out chemicals like sodium, phosphorus, and potassium and release them back to the blood to return to the body. In this way, your kidneys regulate the body's level of these substances. The right balance is necessary for life, but excess levels can be harmful.
Most kidney diseases attack the nephrons, causing them to lose their filtering capacity. Damage to the nephrons may happen quickly, often as the result of injury or poisoning. But most kidney diseases destroy the nephrons slowly and silently. It may take years or even decades for the damage to become apparent.
