More than 26 million American adults have chronic kidney disease. CKD leads to dialysis and heart disease. The main function of the kidneys is to act like a filter for blood. Other functions include the release of three hormones, one that controls blood pressure, one that is responsible for making red blood cells and another hormone that helps maintain a proper balance of calcium in the body.
Blood Filter
Kidneys filter approximately 200 quarts of blood each day. A specialized group of cells in the kidney extract about two quarts of waste products and extra water if necessary from circulating blood. This is then turned into urine.
The filtering capacity of your kidneys can be numerically measured. This number is called a glomerular filtration rate (GFR). It indicates how well your kidneys are functioning. If you have kidney disease, it is important to keep track of your GFR, as it will tell you how well your disease is managed.
Blood Pressure Maintenance
Renin is a hormone produced by the kidneys to help maintain blood pressure. Uncontrolled high blood pressure can damage vital organs like the heart and kidneys. All types of blood pressure medications are effective in lowering blood pressure in CKD. However, it often takes more than one to do the job. According to guidelines issued by the National Kidney Foundation, if you have kidney disease, your target blood pressure should be below 130/80 mm Hg.
Red Blood Cell Production
Erythropoietin is a hormone produced by your kidney. It is needed to stimulate red blood cells in your body. If you kidneys are damaged, you may not be able to produce enough red blood cells, and, as a consequence, you may become anemic. Patients with CKD are susceptible to getting anemia, especially if the CKD progresses. Anemia is very debilitating, can make you feel very tired, lethargic and depressed. The good news is that among the disorders that may afflict patients with CKD, anemia is perhaps the most responsive to treatment.
Vitamin D Balance
Calcitriol is a hormone and a type of vitamin D. Your body gets vitamin D through sunlight or by ingesting it. Your kidneys are needed to convert inactive vitamin D to an active form of vitamin D. If your kidneys are damaged, this mechanism doesn't work, so decreased levels of active vitamin D lead to reduced calcium absorption, which will eventually lead to low calcium in the body. This low vitamin D and calcium generates a cascade of reactions in the body that leads to bone disorders. If you have CKD, ask your doctor to check your vitamin D levels.
References
- JAMA: Determining Prevalence of Chronic Kidney Disease Using Estimated Glomerular Filtration Rate
- NIDDK: The Kidneys and How They Work
- NKF: KDOQI Clinical Practice Guidelines for Chronic Kidney Disease
- NKF: K/DOQI Clinical Practice Guidelines on Hypertension and Antihypertensive Agents in Chronic Kidney Disease
- NKF: KDOQI Clinical Practice Guidelines for Chronic Kidney Disease
