High blood pressure and kidney disease - Pamphlet

Pamphlet by: National Kidney and Urologic Diseases Information Clearinghouse, July 1, 2001

* What is high blood pressure?

* How does high blood pressure hurt my kidneys?

* How will I know whether I have high blood pressure?

* How will I know whether I have kidney damage?

* How can I prevent high blood pressure from damaging my kidneys?

* Are there medicines that can help?

* What groups are at risk for kidney failure related to high blood pressure?

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Your kidneys play a key role in keeping your blood pressure in a healthy range, and blood pressure, in turn, can affect the health of your kidneys. High blood pressure, also called hypertension, can damage the kidneys.

What is high blood pressure?

Blood pressure measures the force of blood against the walls of your blood vessels. Blood pressure that remains high over time is called hypertension. Extra fluid in your body increases the amount of fluid in your blood vessels and makes your blood pressure higher. Narrow or clogged blood vessels also raise blood pressure.

If you have high blood pressure, see your doctor regularly.

How does high blood pressure hurt my kidneys?

High blood pressure makes your heart work harder and, over time, can damage blood vessels throughout your body. If the blood vessels in your kidneys are damaged, they may stop removing wastes and extra fluid from your body. The extra fluid in your blood vessels may then raise blood pressure even more. It's a dangerous cycle.

High blood pressure is one of the leading causes of kidney failure, also commonly called end-stage renal disease (ESRD). People with kidney failure must either receive a kidney transplant or go on dialysis. Every year, high blood pressure causes more than 15,000 new cases of kidney failure in the United States.

How will I know whether I have high blood pressure?

Most people with high blood pressure have no symptoms. The only way to know whether your blood pressure is high is to have a health professional measure it. The result is expressed as two numbers. The top number, which is called the systolic pressure, represents the pressure when your heart is beating. The bottom number, which is called the diastolic pressure, shows the pressure when your heart is resting between beats. Your blood pressure is considered normal if it stays below 130/85 (expressed as "130 over 85"), but recent studies suggest that people with kidney disease should keep their blood pressure even lower.

How will I know whether I have kidney damage?

Kidney damage, like hypertension, can be unnoticeable, detected only through medical tests. Blood tests will show whether your kidneys are removing wastes efficiently. Your doctor may refer to tests for serum creatinine and BUN, which stands for blood urea nitrogen. Having too much creatinine and urea nitrogen in your blood is a sign that you have kidney damage.

Another sign is proteinuria, or protein in your urine. Proteinuria has also been shown to be associated with heart disease and damaged blood vessels. (For more information, see the NIDDK fact sheet on proteinuria.)

How can I prevent high blood pressure from damaging my kidneys?

If you have kidney damage, you should keep your blood pressure well below 130/85. The National Heart, Lung, and Blood Institute (NHLBI), one of the National Institutes of Health (NIH), recommends that people with kidney disease use whatever therapy is necessary, including lifestyle changes and medicines, to keep their blood pressure at or below 130/85, or even below 125/75 when protein in the urine exceeds 1 gram per 24 hours.

How can I control my blood pressure?

NHLBI has found that five lifestyle changes can help control blood pressure:

* Maintain your weight at a level close to normal. Choose fruits, vegetables, grains, and low-fat dairy foods.

* Limit your daily sodium (salt) intake to 2,000 milligrams or lower if you already have high blood pressure. Read nutrition labels on packaged foods to learn how much sodium is in one serving. Keep a sodium diary.

* Get plenty of exercise, which means at least 30 minutes of moderate activity, such as walking, most days of the week.

* Avoid consuming too much alcohol. Men should limit consumption to two drinks (two 12-ounce servings of beer or two 5-ounce servings of wine or two 1.5-ounce servings of "hard" liquor) a day. Women should have no more than a single serving on a given day because metabolic differences make women more susceptible to alcoholic liver disease.

* Limit caffeine intake.

Are there medicines that can help?

Many people need medicine to control high blood pressure. A group of medications called ACE (angiotensin-converting enzyme) inhibitors lower blood pressure and have an added protective effect on the kidney in people with diabetes. Additional studies have shown that ACE inhibitors also reduce proteinuria and slow the progression of kidney damage in people who do not have diabetes. You may need to take a combination of two or more blood pressure medicines to reach 125/75.

What groups are at risk for kidney failure related to high blood pressure?