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.
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.
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.
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.
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) found that people with the metabolic syndrome had a 43 percent increased risk of developing chronic kidney disease than those without the metabolic syndrome.
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. This can be caused by an infection or other process that inflames the glomeruli, which are the blood vessels within the nephrons.
Kidney stones. These 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. This 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.
Once kidney damage starts, it can be slowed, but it can't always be reversed. That's why prevention is crucial. These steps can help keep your kidneys healthy:
Drink plenty of water. Healthy people can let thirst be their guide. If you've already had kidney stones, you may be advised to drink at least three to four quarts of water daily to lessen your risk of forming a new stone.
Eat nutritiously and exercise. You may not associate food and physical activity with kidney disease, but a balanced diet and regular exercise help prevent or control diabetes and high blood pressure, two risk factors for kidney disease. A good eating plan emphasizes fruits, vegetables, whole grains, and nonfat or low-fat dairy products. Protein such as lean meats, poultry, and fish also are part of it. To reduce disease risk, adults should exercise at a moderate pace for 30 minutes or more on most days.
Don't smoke. Cigarette smoking slows the flow of blood to the kidneys. When less blood reaches the kidneys, it impairs their ability to function properly. Smoking also increases the risk of kidney cancer by about 40 percent.
Talk with your doctor about appropriate medical tests. All adults should have their blood pressure checked periodically. If you're at risk for kidney disease, your doctor also may recommend regular blood or urine tests.
Follow your doctor's advice faithfully if you have diabetes or high blood pressure. That includes taking your medications as directed. It may help reduce your risk of long-term complications, such as kidney failure.