1. Kidneys: What Your Kidneys Do for You Contributed by Elaine M. Koontz, RD, LD/N Review Date 8/13 R-0626 Provided Courtesy of Nutrition411.com

2. What Your Kidneys Do for You Remove waste from the body (urea and ammonia) Remove drugs from the body Balance the body’s fluids Regulate electrolyte levels in the body Regulate blood pressure Promote strong, healthy bones Control the production of red blood cells Reabsorb glucose and amino acids

3. Kidneys and Homeostasis The kidneys need to react appropriately to your condition The kidneys have a tough job, for example: – If you are dehydrated, the kidneys put less water in the urine – If your blood is acidic, the kidneys remove more acid from the urine – If your potassium level gets too high, the kidneys remove more potassium from the urine

4. Kidney Anatomy Two kidneys, each the size of a fist, are located at the lowest level of the rib cage, near the middle of the back Each kidney contains roughly a million nephrons Each nephron contains tiny blood vessels known as the glomerulus, which is attached to a tubule Blood enters the kidneys from the liver

5. Kidney Anatomy (cont’d) Blood enters the glomerulus, where it is filtered: – Normal proteins and cells are kept in the bloodstream – Extra fluids and waste pass through the tubule In the tubule, chemicals and water are either added or removed, and eventually are excreted as urine

6. Kidney Anatomy (cont’d) The ureters are muscular tubes attached to the kidneys that carry urine to the bladder Roughly 200 quarts of fluid are filtered every day 2 quarts of waste products and extra water are sifted out

7. Waste The waste that the kidneys filter out comes from the normal breakdown of tissues, such as muscle, and from food After the body has taken what it needs from the food, the waste is sent to the blood and removed by the kidneys If the kidneys are unable to do their job and remove the waste, waste builds up in the body, which can prove very harmful

8. Waste (cont’d) The kidneys collect and get rid of waste in three ways: – Glomerular filtration—the blood is filtered through the glomerulus in the nephron – Tubular reabsorption—the tubules of the nephron reabsorb the filtered blood in the nearby blood vessels – Tubular secretion—the filtrate passes through the tubules and eventually ends up in the bladder

9. Hormones Released by the Kidneys Erythropoietin—stimulates the bone marrow to make red blood cells Renin—regulates blood pressure; released by the adrenal glands, which sit on top of the kidneys Calcitriol—the active form of vitamin D, which helps maintain calcium for bones and normal chemical balance in the body

10. Measuring Kidney Function If kidney function decreases by 30% to 40%, the effects are rarely noticeable When a person has <25% of kidney function, serious health problems occur When a person has <10% to 15% of kidney function, dialysis or a kidney transplant becomes necessary The estimated glomerular filtration rate (eGFR) is used to measure kidney function (the rate at which the glomeruli filter the blood)

11. StageDescriptionGFR (mL/min/1.73 m 2 1Slight kidney damage with increased or normal filtration >90 2Mild decrease in kidney function 60-89 3Moderate decrease in kidney function 30-59 4Severe decrease in kidney function 15-29 5Kidney failure requiring dialysis or transplantation <15 Stages of Chronic Kidney Disease GFR=glomerular filtration rate, m 2 =meters squared, mL=milliliter, min=minute

12. Most Common Causes of Kidney Disease Diabetes—unused glucose in the bloodstream damages the nephrons High blood pressure—high blood pressure damages the vessels of the kidneys; the vessels become unable to filter fluid and waste Glomerular diseases—include autoimmune diseases, infection-related diseases (such as pyelonephritis), and sclerotic diseases – Immune diseases that can lead to kidney disease include lupus, HIV/AIDS, hepatitis B, and hepatitis C HIV/AIDS=human immunodeficiency virus/acquired immunodeficiency syndrome

13. Most Common Causes of Kidney Disease (cont’d) Inherited and congenital kidney disease— includes polycystic kidney disease Poisons Trauma Certain medications

14. Acute Kidney Failure Acute kidney failure occurs very quickly A person can recover in some cases, but it also can lead to a permanent loss of kidney function

15. Acute Kidney Failure (cont’d) Causes of acute kidney failure: – Injury – Blood infection (septicemia) – Blood loss – Obstruction of urine flow – Pregnancy complications – Sudden breakdown of muscle tissue – Sometimes occurs in dehydrated athletes

16. Symptoms in Later Stages of Kidney Disease Frequent urination Fatigue Loss of appetite Nausea and vomiting Swelling of the hands and feet Feeling itchy Feeling numb Having difficulty concentrating Suffering from muscle cramps Darkening of skin tone

17. Tests for Kidney Disease Blood pressure—high blood pressure can cause kidney disease or indicate that someone may already have kidney disease Microalbuminuria and proteinuria—when healthy kidneys take waste from the blood, they leave these proteins in the blood; if these proteins show up in the urine, it is a sign that kidney function is impaired

18. Tests for Kidney Disease (cont’d) Blood urea nitrogen—healthy kidneys remove urea from the blood, which is excreted in the urine; having urea in the blood is a sign of impaired kidney function

19. Resources Hoenig DM. Kidney anatomy. http://emedicine.medscape.com/article/1948775- overview. Medscape Reference Web site. Accessed August 22, 2013.http://emedicine.medscape.com/article/1948775- overview How your kidneys work: why are the kidneys so important? National Kidney Foundation  Web site. http://www.kidney.org/kidneydisease/howkidneyswrk.cfm. Accessed August 22, 2013.http://www.kidney.org/kidneydisease/howkidneyswrk.cfm Kidney anatomy and function. HealthPages.org Web site. http://healthpages.org/anatomy-function/kidney/. Accessed August 22, 2013. http://healthpages.org/anatomy-function/kidney/ National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health. The kidneys and how they work. National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) Web site. http://kidney.niddk.nih.gov/kudiseases/pubs/yourkidneys/. Updated March 23, 2012. Accessed August 22, 2013. http://kidney.niddk.nih.gov/kudiseases/pubs/yourkidneys/ Understanding kidney disease—the basics. WebMD ® Web site. http://www.webmd.com/a-to-z-guides/understanding-kidney-disease-basic- information. Accessed August 22, 2013. http://www.webmd.com/a-to-z-guides/understanding-kidney-disease-basic- information