A proper working kidney has a lot of important functions in the body. The main function of a kidney is to act like a filter for blood. Proper working kidneys also control blood pressure, red blood cell production and calcium balance. Damaged kidneys lead to chronic kidney disease (CKD), one of the leading causes of death in the United States.
Filtering Blood
Your kidneys filter about 200 quarts of blood each day. A specialized group of cells in the kidney extracts about 2 quarts of waste products and extra water, if necessary, from circulating blood. It's possible to measure the filtering capacity of your kidneys. This filtering capacity generates a number called glomerular filtration rate (GFR). This number indicates how well your kidneys are working. If you have chronic kidney disease, it's important to keep track of your GFR because it will tell you how well your disease is managed. Ask your doctor what your GFR number is.
Maintaining Blood Pressure
Renin is a hormone produced by your kidneys to help maintain blood pressure. Uncontrolled high blood pressure can damage vital organs such as the heart and kidneys. According to guidelines issued by the National Kidney Foundation, if you have kidney disease, your target blood pressure should be below 130/80mm Hg. All types of blood pressure medications are generally effective in lowering blood pressure in CKD. However, it often takes more than one to do the job.
Controlling Red Blood Cell Production
Erythropoietin is a hormone produced by your kidney that's needed to stimulate red blood cells in your body. If your kidneys are damaged, you may not be able to produce enough red blood cells. This may make you become anemic. If left untreated, anemia can become very serious. It can make you feel very tired, lethargic and depressed. However, among the disorders that may afflict patients with CKD, anemia is perhaps the most responsive to treatment. Ask your doctor to check if you are anemic.
Maintaining Vitamin D Balance
Calcitriol is a type of vitamin D. You can get vitamin D naturally by exposing yourself to sunshine, or you can take vitamin D tablets. Normal working kidneys convert inactive vitamin D to an active form of it. If your kidneys are damaged, this mechanism doesn't work and so decreased levels of vitamin D lead to low calcium levels in the body. Low vitamin D and calcium in the body together generate a cascade of reaction that can lead to bone disorders. If you have CKD, ask your doctor to check your vitamin D levels.
References
- Ref 1 NIDDK: Kidneys filter 200 quarts of blood
- Ref 2 CDC: Ninth leading cause of death in US
- Ref 3. NKF: KDOQI Clinical Practice Guidelines for Chronic Kidney Disease
- Ref 4. NKF: K/DOQI Clinical Practice Guidelines on Hypertension and Antihypertensive Agents in Chronic Kidney Disease
- Ref 5. Kidney International: Vitamin D
