Your kidneys are your body's filters. They remove waste and excess fluid from your blood. People who have high blood pressure and diabetes are at higher risk for kidney disease because of the way these conditions damage the blood vessels and other parts of these vital organs.
An important job
The kidneys work by cleaning your blood as it passes through tiny filtering units known as nephrons. These filters process important chemicals and nutrients, and they remove wastes such as urea and creatinine, which are left over when protein is broken down. Whatever your body doesn't need is eliminated in urine. If these wastes aren't removed, they can accumulate and make you sick.
Your kidneys help balance the amount of chemicals—such as sodium, phosphorus, and potassium—in your blood. The right levels of these chemicals are essential for good health. The kidneys also release two important hormones called erythropoietin and renin. Erythropoietin stimulates the production of red blood cells in bone marrow. Renin regulates blood pressure.
Causes and symptoms of kidney disease
Diabetes and high blood pressure are the two main causes of kidney disease and kidney failure, especially if they're not well-controlled. According to the National Kidney Foundation, about 30 percent of people with type 1 diabetes and 10 to 40 percent of people with type 2 diabetes will eventually have kidney failure. Type 2 diabetes often produces symptoms that are so subtle and develop so gradually that they're easy to miss. High blood pressure usually doesn't produce any symptoms.
Diabetes and high blood pressure can cause damage to the nephrons. Often, this occurs gradually over years. You may not realize what's happening until the damage is severe enough to cause obvious symptoms. These may include puffiness around your eyes, or swelling in your hands or feet. Contact your doctor promptly if you see any of these warning signs. Blood and urine tests can tell you whether there's a problem with your kidneys.
People at higher risk
Controlling diabetes and the high blood pressure that often results are important to maintaining your overall kidney health. Metabolic syndrome, a condition that frequently precedes and accompanies type 2 diabetes, is also a serious risk factor.
Researchers recently concluded a nine-year study on 11,000 people who had normal kidney function and were screened for the five traits of the metabolic syndrome: high blood glucose; high blood pressure; high triglycerides; low HDL, or "good," cholesterol; and a large waist. "People with at least three traits had a 43 percent increased risk of developing chronic kidney disease," says lead author Manjula Kurella, M.D.
Having a parent or sibling with kidney disease also increases the odds that you'll develop it. The chance of developing the condition increases as you grow older, too. In addition, chronic kidney disease is more common in African Americans, Hispanics, Asians, and American Indians. These groups are also more likely to develop type 2 diabetes.
Kidney disease can take several forms, depending on the cause:
Glomerulonephritis can be caused by an infection that inflames the glomeruli, the blood vessels within the nephrons.
Kidney stones are hard, crystallized masses that build up within the kidneys. Such masses form when there's an imbalance between certain chemicals in urine that promote crystallization and other chemicals that inhibit it. Left untreated, kidney stones eventually can damage the kidneys.
Polycystic kidney disease is an inherited condition in which numerous cysts grow inside the kidneys. Over time, the cysts can crowd out working kidney tissue.
Injuries, poisons, and some medications also can cause kidney damage. Heavy or long-term use of products that contain a mixture of aspirin, acetaminophen, and other medications (such as ibuprofen or caffeine) has been found to be most risky.