High Blood Pressure and Kidney Disease: How Are They Connected?

High Blood Pressure and Kidney Disease: How Are They Connected?

Participants
Lisa Clark , Jai Radhakrish MD, MRCP (, Leonard Stern MD, Rakhi Khanna DO

For webcast go to http://www.healthline.com/hgy-transcripts/blood-pressure-and-kidneys and click Play video

Summary
It's no secret that high blood pressure, or hypertension, is a serious medical problem. But most people think hypertension is mainly a risk factor for heart attack or stroke. In fact, unchecked high blood pressure might also put you in danger of developing kidney disease. Join our panel as they discuss the dangers of high blood pressure, and offer measures you can take to cut your risks of developing kidney disease.

Webcast Transcript
LISA CLARK: I'm Lisa Clark. Welcome, and thanks for joining us for our webcast. It's no secret that high blood pressure, or hypertension, is a serious medical problem, but most people think hypertension is mainly a risk factor for heart attack or stroke. In fact, unchecked high blood pressure might also put you in danger of developing kidney disease. For the next few minutes we'll take a look at how dangerous this can be and look at ways that you can cut your risk.

Joining our discussion this evening, Dr. Leonard Stern. Welcome, and thank you for joining us. Also, Dr. Jai Radhakrishnan. Welcome. Thanks for being here.

I guess we should start with a basic discussion of hypertension. Jai, I'll throw that one to you.

JAI RADHAKRISHNAN, MD: Hypertension refers to high blood pressure, very simply, so the question obviously comes up, "Is there a magic number above or which we say blood pressure is normal?" It's really a function of trials that have looked at outcomes and measuring what blood pressure is associated with a bad outcome. Currently our definition of hypertension is if the top, or systolic, blood pressure is over 140 and of the bottom, or diastolic, blood pressure is over 90 mm of mercury.

LISA CLARK: This is not related to whatever your heartbeat rate might be. This is a completely different measurement.

JAI RADHAKRISHNAN, MD: Blood pressure is really a composite measurement of what the heart puts out, which is cardiac output, and how tightly the blood vessels are squeezed, which is vascular resistance. So blood pressure is essentially a product of these two factors. So you could have a high blood pressure if the heart output goes up or if the vessels are tightly squeezed.

LISA CLARK: Len, high blood pressure is often called the silent killer, and as a result many people are unaware they have the problem. While we're staying with this topic, let's talk about some of the risk factors for hypertension.

LEONARD STERN, MD: One main risk factor is genetics. There is something which we call essential hypertension, and the reason we call it essential is we have no understanding of the causative factors. We presume that this is a genetic multifactorial disorder that exists in families. A very small percentage of people will develop hypertension, which we call secondary hypertension, where they have a specific cause. Their blood vessels are abnormal in their kidney. They have an inflammatory disorder of their kidney that raises their blood pressure. They have some injury to the blood vessels or a congenital anomaly of their blood vessels, a disorder of the heart or some endocrine function. Those are readily identifiable and treatable.

Essential hypertension, on the other hand, generally presents in an asymptomatic way, and the only way the patient would really ever know they have this illness is when they go to the physician for routine screening. In essence it's silent, because unless the patient has their blood pressure checked, either by themselves or in the physician's office, they're not going to know until they have some cardiovascular event.

But from my perspective, a normal blood pressure is unique in an individual. It could be any number. Some patients have normal blood pressures of 120/80, and any blood pressure higher than that is abnormal. Others may even have lower blood pressures, and some people with specific blood vessel problems may even have normal blood pressures that are a bit higher than 140/90.

LISA CLARK: Jai, let's just, for argument's sake, say that someone does qualify as having hypertension, whatever the number is.
What is the correlation between that condition and the risk of kidney disease?

JAI RADHAKRISHNAN, MD: It's a direct correlation, so if you were to plot a graph, you would see the higher the blood pressure, the higher the chances of getting kidney damage.

LISA CLARK: But which comes first?

JAI RADHAKRISHNAN, MD: That's always the magic question. Both answers are correct. A higher blood pressure could lead to kidney damage, especially if it's really high and over a long period of time it's not being treated, and on the other side, if you have kidney damage, you could retain salt and water, amongst other mechanisms, and that could cause the heart output to go up and give you high blood pressure. So both are equally true, and both need to be addressed individually.

LISA CLARK: What is the mechanism of high blood pressure in the body that might have an impact on kidney function? What's happening in your body when you have high blood pressure?

LEONARD STERN, MD: High blood pressure per se causes a reaction in the blood vessels, and the blood flow to the kidney is reduced. The higher the blood pressure, the more blood flow to the kidney is reduced, impairing the function of the kidney. The kidney is a filtering organ which is dependent on blood flow being delivered to the kidney to provide that function, so if we reduce the blood flow, we reduce the ability the kidney to maintain our internal homeostasis and to provide its excretory function.

LISA CLARK: So regardless of which came first, the hypertension or the kidney disease, your advice when you see a kidney patient with high blood pressure is to bring the blood pressure down?

JAI RADHAKRISHNAN, MD: That is absolutely correct, and there's a lot of data, including patients with diabetes or high blood pressure itself, that if you don't treat the pressure very aggressively, the chance of lasting kidney damage is very real.

LISA CLARK: There are steps that people can take on their own to reduce high blood pressure, lifestyle type changes?

JAI RADHAKRISHNAN, MD: These are very important and should be tried first, especially in patients who have mild elevation of blood pressure, and this includes a good diet. There's something called the DASH diet, which is easily applicable to most patients. It's not too restrictive. Salt restriction is a little controversial, and most experts would say moderate salt restriction is important in trying to control, especially, mild high blood pressure. Aerobic exercise on a daily or at least a twice-weekly basis is very important. Weight reduction. Controlling smoking, so try to avoid smoking completely if you definitely have high blood pressure. Sometimes, the use of alternative medicine therapies have been propagated to be useful, especially relaxation techniques or mediation.

LISA CLARK: When those efforts aren't enough, what sorts of things might doctors prescribe to help lower blood pressure?

LEONARD STERN, MD: Obviously, medications play an important role in the control of blood pressure, but the issue with medications has been that traditionally medications have been difficult to provide because of side effect profiles. It's very difficult to treat a patient with a silent illness where they have felt well with a medication that provided numerous side effects, not the least of which were fatigue and sexual dysfunction.

Today we have a few better agents that can provide controlled blood pressure with few, if any, side effects.

But here, again, the same issue applies, that the treatment of blood pressure requires that the blood pressure be actually controlled, so sometimes that takes more than one agent -- two, even three drugs -- to reach the target blood pressure control that we aim for.

How do we know we have that? I try to teach patients to measure their own blood pressure, because many times the readings that they have in the home setting or in their work setting are more reliable than the ones that they have in the doctor's office. They always talk about this "white coat effect" where the blood pressure is elevated in the doctor's office. It's substantially lower at home. What I try to do is train patients to measure their blood pressure frequently so they can get an average of what their readings are over a week's period.

LISA CLARK: I want to ask you specifically about some of the types of drugs that might be prescribed. ACE inhibitors -- are those particularly effective for people who also have kidney disease as well as hypertension?

JAI RADHAKRISHNAN, MD: Yes. The advantage of ACE inhibitors is that even if you don't have a high blood pressure, it reduces the pressure within the kidney and thereby reduces the stress on the kidney. So if you have a patient who has a high blood pressure and has kidney dysfunction, this is probably the first drug you should consider treating the patient with. There's also a sort of allied agent called ARB, or angiotensin receptor blocker, which is very similar to an ACE inhibitor and which may have less side effects. So both of these drugs are extremely important in treatment of patients with high blood pressure and kidney disease.

LISA CLARK: Is it ever a consideration that because kidney function is impaired and the system is not able to filter as effectively that you wouldn't choose certain types of drugs that might otherwise be used if there's just high blood pressure on the table?

LEONARD STERN, MD: These two drugs, the classes of drugs that we just talked about, the ACE inhibitors and the ARBs, are superb first-line agents for treatment of high blood pressure and for preservation of kidney function, but when kidney disease is far advanced, then these drugs have limited uses, because part of their mechanism of action is they impair the ability to excrete potassium.

LISA CLARK: Thank you, both of you, Dr. Leonard Stern, Dr. Jai Radhakrishnan, and thanks to you for joining us in our web audience. I'm Lisa Clark.

Read more: http://www.healthline.com/hgy-transcripts/blood-pressure-and-kidneys/3#ixzz113NSzmtM
Healthline.com - Connect to Better Health