The kidneys are two organs located in your midsection on either side of your spine in the middle of your back, just above the waist. They clean your blood, keep the balance of salt and minerals in your blood, and help control blood pressure.
When your kidneys are damaged, waste products and fluid can build up in your body, causing swelling in your ankles, vomiting, weakness, poor sleep, and shortness of breath. If you don't treat them, diseased kidneys may eventually stop working completely. Loss of kidney function is a serious -- and potentially fatal -- condition.
Creatinine is a waste product from the normal breakdown of muscle tissue. As creatinine is produced, it's filtered through the kidneys and excreted in urine. Doctors measure the blood creatinine level as a test of kidney function. The kidneys' ability to handle creatinine is called the creatinine clearance rate, which helps to estimate the glomerular filtration rate (GFR) -- the rate of blood flow through the kidneys.
Marathon runners and other athletes who don't drink enough fluids while competing in long-distance endurance events may get acute renal failure because of a sudden breakdown of muscle tissue. This releases a large amount of protein into the bloodstream called myoglobin that can damage the kidneys.
What Causes Chronic Kidney Disease?
Kidneys that don't work well for longer than 3 months is called chronic kidney disease (CKD). It's dangerous, because you may not have any symptoms until a lot of damage, that often can't be repaired, has happened.