By Jennifer Weil, MD

Hypertension (high blood pressure) and kidney disease are like the chicken and the egg; it’s hard to know which came first, because they are almost always found together. For some people, hypertension is the main cause of their chronic kidney disease (CKD). For others, kidney disease comes first and then blood pressure goes up. When it comes to treatment, however, it doesn’t matter which came first. The National Kidney Foundation (NKF) recommends a blood pressure goal of less than 130/80 mmHg for people with CKD. Some patients benefit from even lower blood pressures.

Evidence is overwhelming that hypertension contributes to the worsening of kidney function over time. High blood pressure makes the kidneys fail more rapidly, regardless of a patient’s sex, race, age and cause of kidney disease. However, the evidence is also overwhelming that adequate treatment of high blood pressure slows the progression of kidney disease. In fact, lowering blood pressure is one of the best things a person can do to extend the functional life of his or her kidneys!

High blood pressure also causes other complications, such as heart disease and stroke. Patients can die of heart attacks and stroke even when their kidney disease is still in its early stages. So treatment of hypertension is essential not only to slow the progression of kidney disease, but to prevent cardiovascular complications and perhaps early death.

High blood pressure is nicknamed “the silent killer” because there are often no symptoms. While some people experience headaches or dizziness, the majority of people with high blood pressure feel just fine. The only way to know for sure if blood pressure is elevated is to measure it! A home blood pressure cuff is a very useful tool for people with CKD. Patients should bring their cuffs with them to the doctor so they can check their machine against the one in the doctor’s office and be sure their home readings are correct. It’s also helpful for patients to write down blood pressure measurements made at home and bring those readings to office visits where they can review the numbers with the doctor or nurse.

The blood pressure measurement has two numbers – systolic (sis-tah’-lick) and diastolic (di^-ah-stah’-lick). The systolic pressure is the first number, which is the pressure in the blood vessels while the heart is pumping blood. The diastolic pressure is the second number, which is the pressure in the blood vessels while the heart is resting between beats. Since people with CKD are advised to keep their blood pressure below 130/80 mm Hg, numbers higher than 130 for systolic and higher than 80 for diastolic are considered too high.

There are two general ways to lower blood pressure: lifestyle changes and medication. Lifestyle changes include low sodium diet, moderation of alcohol consumption, exercise and weight loss. However, most patients with CKD also require medication to control blood pressure. A combination of lifestyle changes and medication(s) is usually most effective!

There are many different medicines used to treat high blood pressure. The drugs are organized by categories, which means all members of a given category have similar chemical structures and act in similar ways in the body (see table). Within each category, drugs may differ by duration of effect, manufacturer and cost. Generally, side effects are similar among drugs in the same category. Many categories of blood pressure medicine have extra benefits beyond lowering blood pressure, and therapy should be individualized for patients who might have problems beside kidney disease and hypertension. For example, people with diabetes should take medicines in either the class angiotensin converting enzyme (ACE) inhibitors or the class angiotensin receptor blockers (ARBs) because these drugs provide an extra benefit by slowing diabetic kidney disease. People with protein in their urine also should take drugs in these categories because they decrease the amount of protein in the urine. People with heart disease should take drugs from the class beta-blockers. People with swelling from extra fluid often need a drug from the class diuretics.

Categories of Blood Pressure Drugs, How They Work and Extra Benefits

Reprinted with permission from JNC-VII, National Heart, Lung, and Blood Institute, National Institutes of Health.

The best medication is the one that lowers blood pressure, provides extra benefits if needed, and has minimum side effects. Since every person is different, it is sometimes necessary to switch among drugs within a class or from one class to another to get the best response. It is often better to take a low dose of two different medicines from different classes than a high dose of a single pill. This strategy tends to minimize the side effects a person may get from a high dose of just one medication. It also tends to lower blood pressure more effectively. Most people with CKD will require two or more drugs, along with lifestyle changes, to meet the blood pressure goal of less than 130/80 mm Hg.

Until the blood pressure has fallen to below 130/80 mmHg, it may be necessary to see a health care provider every two weeks to make adjustments in lifestyle and medicines. After the goal has been reached, visits with the doctor or nurse every month for three months will help to maintain blood pressure at goal. If the blood pressure remains stable below the target of 130/80 mmHg, visits can be less frequent. The doctor should also check how the kidneys are responding to the lowered blood pressure.

You can request a My Blood Pressure wallet card by contacting the National Heart, Lung, and Blood Institute at 301-592-8573. This research was supported in part by the Intramural Research Program of the NIH, NIDDK.

Dr. Weil is a nephrologist and staff clinician with the National Institutes of Health. Her main interest is diabetic kidney disease among vulnerable populations within the U.S., as well as the developing world.

This article originally appeared in the March/April 2006 issue of Kidney Beginnings: The Magazine, Vol. 5, No. 1.

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