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Secondary Hypertension Causes

Secondary Hypertension Causes

As a family physician essential hypertension is the most common chronic health problem seen in the office.  Most patients with hypertension have essential hypertension, meaning they just have high blood pressure without another underlying identifiable medical problem causing the hypertension.  It’s estimated that 5-10% of adults with hypertension have secondary hypertension.  This means that they have a medical condition that is causing their blood pressure to be high.  In catching up with my AFP reading I found a very good review article in the Dec. 15, 2010 issue by Viera and Neutze titled, “Diagnosis of Secondary Hypertension: An Age-Based Approach.”

About one third of US adults have hypertension.  If the above stats are correct then about 1.6-3.2% of adult Americans have secondary hypertension.  The trick is to figure out who these patients are, make their diagnosis and make appropriate interventions to treat their underlying cause of hypertension.  That’s no small task.  The authors suggest taking an age related approach to index of suspicion and evaluation.  This is nothing new, but I did learn a few things that I want to share.

In children under age 12 with hypertension it’s estimated that over half, maybe up to 85% of hypertension is from a secondary cause.  Therefore all children with hypertension need a careful evaluation for underlying causes.  By far the most common underlying cause in children is renal parenchymal disease, often caused by glomerulonephritis, congenital problems, and vesicoureteral reflux.  In children and very young adults evaluation for these problems should consist of a BUN, creatinine, urine analysis and culture, and renal imaging with ultrasonography.  The other common cause to consider is coarctation of the aorta, usually able to be diagnosed in children if it is considered by transthoracic ultrasonography in combination with physical findings of hypertension and usually a systolic murmur.  In adults a chest x-ray can show classic findings and often an MRI is used to confirm the diagnosis.

In young adults with hypertension only about 5% of hypertension is secondary hypertension.  Especially in women, renal artery stenosis from fibromuscular dysplasia is the most common cause of secondary hypertension.  Sometimes a high-pitched holosystolic renal artery bruit can be heard.  Diagnosis is usually made with an MRI with gadolinium contrast or with CT angiography.

In adults age 40-64 about 10% of patients have secondary hypertension.  I was surprised to learn that this is the most common cause of secondary hypertension in this age group, being the cause of up to 6% of hypertension.  I also was surprised to learn that only 30% of patients with hyperaldosteronism can be found by lab screening of potassium prior to treatment (low in primary hyperaldosteronism). The best initial screening test is an aldosterone/renin ratio done in the upright position at least 2 hours after waking.  A ratio of above 20 (aldosterone in ng/dl and renin in ng/ml) along with an aldosterone level above 15 ng/dl is suggestive of hyperaldosteronism, and needs endocrinologic confirmation with one of the salt suppression tests.

Sleep apnea needs to be considered in all age groups with hypertension, especially refractory hypertension, as does alcoholism and illicit drug use.

The secondary cause of hypertension physicians seem to have the highest index of suspicion for, pheochromocytoma, is relatively rare, causing only about 1/200 cases of secondary hypertension, or about one in 2-4000 cases of hypertension.

When hypertension starts after age 65 the chances of secondary hypertension again go up to about 17%, most caused by renal artery stenosis from atherosclerosis.   Clues to look for this are known atherosclerosis elsewhere, age over 50, rapid deterioration of renal function as measured by a rise of >0.5 in serum creatinine after starting an ACE or ARB drug, or unexplained renal insufficiency.

The other common cause of secondary hypertension in older adults is renal insufficiency from any of many causes.

So in summary things I learned or relearned from this nice review are:

  • In kids <12 years old most hypertension is secondary and from renal parenchymal disease
  • In middle age adults screen for hyperaldosteronism with a aldosterone/renin ratio
  • In older adults think about renal artery stenosis from atherosclerosis
  • Always consider sleep apnea if hypertension is tough to control

Let’s all bear down and do better with hypertension.  As a nation we do very poorly, with up to 30% of hypertensive patients undiagnosed and over 50% sub-optimally controlled(1).

Blood Pressure Control: No Excuses. Just Do It!

A good argument can be made that we could save more lives and prevent more morbidity by aggressively diagnosing, treating and controlling hypertension than with any other condition given the knowledge and tools at our disposal at this time. Hypertension is not a sexy to address as things like breast cancer, colon cancer or diabetes, but it is extremely prevalent,we can diagnose it easily, treat it effectively, and we have great data that this treatment saves lives and prevents morbidity from strokes, heart attacks, congestive heart failure and kidney failure.

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) tells us that hypertension affects more than 50 million Americans and more than 1 billion persons worldwide. It is estimated that in people with Stage I Hypertension (the mildest type with Systolic BP of 140-159 or diastolic BP of 90-99 at the time of diagnosis) we only need to treat 11 people for 10 years to prevent one cardiovascular death. If look at people with either known cardiovascular disease or any organ damage from high blood pressure it only takes treating 9 people for 10 years to prevent a death.

The bad news is that despite this terrific data, and despite better and better drugs to treat hypertension we are doing a miserably poor job of controlling hypertension in America.  After great progress in the 1970’s and 1980’s we have made little progress in the control of hypertension.  In the late 1970’s only 51% or Americans with Hypertension were aware of the diagnosis and only 10% were controlled.  By the late 1980’s this had dramatically improved to 73% awareness and 29% controlled.  Since then there has been little continued progress.  Data from the early 1990’s and from 1999-2000 show little further improvement, and there is not much evidence we are doing better now.  Effective control of only 30% of patients with a disease that is nearly 100% controllable and where effective control can prevent death and terrible diseases like stroke, heart attacks and kidney failure is a disgrace. We should and can do better.

The JNC-7 report states the goals succinctly:

Goals of Therapy

The ultimate public health goal of antihypertensive therapy is the reduction of cardiovascular and renal morbidity and mortality. Since most persons with hypertension, especially those age >50 years, will reach the DBP goal once SBP is at goal, the primary focus should be on achieving the SBP goal. Treating SBP and DBP to targets that are <140/90 mmHg is associated with a decrease in CVD complications. In patients with hypertension and diabetes or renal disease, the BP goal is <130/80 mmHg.

This sounds simple.  It really is most of the time so why are we failing miserably? Here is what I think:

  1. As a population Americans, both patients and physicians just don’t believe treatment of hypertension is important.  Every day I hear patients say, “I’ve always had borderline blood pressure.”  “I just don’t want to have to take a medication for the rest of my life.”  “My blood pressure is only high at the doctor’s office.”  As physicians we need to be believe the data, be firm in our advice, and not let patients convince us to ignore this serious disease. As patients we need to recognize that when we have high blood pressure it needs effective treatment, and though non-pharmaceutical measures can help, medication is often needed.
  2. Hypertension is asymptomatic, meaning patients feel fine even though their blood pressure is high, and it is gradually causing damage to their blood vessels, heart, and kidneys.  We need to emphasize to patients that they cannot ignore the objective evidence of their disease.  It needs treatment.
  3. Once diagnosed patients drop out of site.  At our office we have had an electronic medical record for 12 years, and have a virtual disease registry to try to track down and arrange follow up on our patients with high blood pressure who have not been in for evaluation and treatment, as well as find patients whose last blood pressures were high but did not come back for reevaluation.  I understand the argument for asking patients to be responsible for their own follow up care, but when we have the tools to help, we should use them.
  4. Too many Americans do not have health insurance, and spending one’s limited money to treat an asymptomatic disease that is not likely to cause problems in any given short period of time is difficult.  I’d argue that we have inexpensive meds that work great for most patients, and there may not be any disease more important to treat than hypertension.  Hypertension treatment should really be at the top of the list of health concerns on which to spend limited resources.

So what should you do as a patient?  Everyone should get a blood pressure check every year or two.  It is free, easy and painless. Just do it.  If your blood pressure is borderline or high don’t wait.  See your physician and get it evaluated.  If your physician seems to not address a blood pressure over 140 systolic on repeated measurements seriously, ask them why?  If they still ignore the problem, consider a different physician or get a second opinion.

 As physicians we need to refocus on the diagnosis and aggressive treatment of this silent killer.  We cannot accept suboptimal control, and need to develop tools to try to manage both our individual patients as well as our patient panel as a whole using a chronic disease management model of care.

What are the common causes of preventable death in the US?

Most people can guess smoking is #1.

But can you guess #2

Think a minute and look at the rest of this post.  Comment if you are surprised. 

Salt reduction makes the news

Now evidence shows that modest salt intake reduction may lead to huge public health benefits and healthcare cost savings.  Strokes and kidney failure, common complications of high blood pressure, are both devastating to individuals and their families, as well as tremendously  expensive.  Since most of the salt in our diet is in prepared or packaged food we eat, to make salt reduction happen I think one or more major food manufacturers will need to market a brand of food that is universally low in sodium.  Imagine how nice it would be to shop and just buy most of your canned, frozen and prepared foods at a competitive price an know that they were lower in salt without having to put your reading glasses on to read the fine print in the ingredients label.   The Wall Street Journal yesterday had an excellent article discussing the research results.  Read on if you’d like to check it out.

  • JANUARY 21, 2010

By SHIRLEY S. WANG

A national program to reduce dietary salt could prevent tens of thousands of heart attacks, strokes and deaths and trim as much as $24 billion from the U.S. health-care tab, according to a study published Wednesday in the New England Journal of Medicine.