What Is Hypertensive Chronic Kidney Disease?

Hypertension, commonly known as high blood pressure, is a major risk factor for many different diseases, including heart disease, stroke, and dementia. Hypertension is also associated with chronic kidney disease (CKD) both as a cause and effect.

On the one hand, uncontrolled hypertension can cause the narrowing of blood vessels servicing the kidneys, decreasing blood flow and increasing kidney damage. On the other, kidneys damaged by CKD are less able to clear fluids from the body, causing a buildup of fluid that increases blood pressure.

Renal hypertension is the term used to describe high blood pressure caused by the narrowing of arteries that transport blood to the kidneys. It is a condition that indicates a significant progression of CKD and the need for immediate treatment to preserve the functions of the kidneys,

This article takes a look at the symptoms and causes of renal hypertension as well as the tests used to diagnose this complication of advanced renal (kidney) disease. It also explores the treatments that can slow the progression of CKD, including medications and specialist procedures.

Causes and Risk Factors of Hypertensive Chronic Kidney Disease

Chronic kidney disease (CKD) is a persistent kidney disease that reduces the rate at which kidneys filter waste and fluids (as measured by the glomerular filtration rate, or GFR) accompanied by an increase in the amount of protein passed in urine (referred to as albuminuria).

According to the Centers for Disease Control and Prevention (CDC), CKD affects 1 in 7 adults in the United States. Increases in the rate of CKD in recent decades have been attributed to an aging population along with increased rates of obesity, diabetes, and hypertension.

CKD and high blood pressure make for a deadly combination. Research suggests that 85% to 95% of people with mild to moderate CKD have clinical hypertension. Hypertension not only speeds the progression of CKD but is considered the second leading cause of end-stage renal disease (in which dialysis or a kidney transplant is needed for a person to survive).

Causes of Renal Hypertension

Renal hypertension, also known as renovascular hypertension, is one of the more common forms of secondary hypertension. Unlike primary hypertension which occurs in the absence of other medical conditions, secondary hypertension is high blood pressure caused by another condition.

Renal hypertension develops when the narrowing of the arteries servicing the kidneys (referred to as renal artery stenosis) alters one of the major functions of the kidneys, namely the regulation of blood pressure.

When most people think about the kidneys, they generally regard them as the filtration system of the body. But, the kidneys are also responsible for maintaining fluid levels and, by doing so, help regulate blood pressure.

When renal artery stenosis occurs, the kidneys will respond to the reduced blood flow as if the body were experiencing dehydration, releasing a hormone called renin that triggers an increase in sodium levels. This causes water in the body to be retained which, in turn, increases blood pressure.

Renal artery stenosis is most commonly caused by atherosclerosis, the hardening and narrowing of arteries due to the buildup of plaque. Less commonly, it is caused by a disorder called fibromuscular dysplasia in which blood vessels throughout the body become fibrous and twisted.

Risk Factors for Renal Hypertension

According to a 2019 review from Mayo Clinic, renovascular hypertension accounts for between 1% and 5% of all cases of hypertension in the general U.S. population. The condition is most commonly seen in people with significant renal artery stenosis (greater than 60% obstruction).

Renal hypertension tends to affect adults over 65, although it can occur in people of any age. Around 90% of cases are caused by atherosclerosis, while 9% are linked to fibromuscular dysplasia. The risk factors vary by the underlying cause.

With atherosclerosis, the risk factors are similar to those for all heart diseases:

• High blood pressure
• High cholesterol
• Smoking
• Diabetes
• Obesity
• Physical inactivity
• A high saturated fat diet

With fibromuscular dysplasia, females tend to be affected far more than males. Unlike atherosclerosis, most cases are diagnosed after 50. Smoking appears to increase the severity of the disease. Genetics is also thought to play a part.

Signs and Symptoms of Hypertensive Chronic Kidney Disease

Renal hypertension will often go unnoticed until signs of the disease are recognized on routine medical tests. In some cases, the condition may only be suspected when a person with high blood pressure doesn't respond to antihypertensive drugs.

As renal hypertension progresses and blood flow to the kidneys is significantly reduced, other, more overt symptoms may develop, including:

• Headache
• Chronic fatigue
• Nausea
• Weakness
• Shortness of breath
• Persistently puffy eyes
• Nosebleeds
• Decreased urine output
• Fluid retention in the legs and feet
  
• Blurry vision or double vision
• Ringing in the ears
• Blood in urine
• Confusion
• Chest pain
• Irregular heartbeat

Even so, most cases of renal hypertension will be asymptomatic (without symptoms) until the condition is well advanced.

According to the CDC, around 90% of the 37 million people living with chronic kidney disease in the United States are wholly unaware of their condition.

Complications of Renal Hypertension

If left untreated, renal hypertension can affect multiple organs. Persistently high blood pressure can place undue stress on blood vessels, causing them to rupture or bulge. It can also cause changes in organs that can lead them to fail or underperform.

Possible complications of renal hypertension include:

• Aneurysm: A bulge in a blood vessel caused by a weakness in the blood vessel wall
• Congestive heart failure: A serious condition in which the heart doesn't pump blood as efficiently as it should
  
• Kidney failure: The last stage of CKD in which the kidneys stop working and dialysis or a kidney transplant is required for you to survive
• Left ventricular hypertrophy: The thickening of the wall of the heart's main pumping chamber
• Myocardial infarction: Also known as a heart attack
• Pulmonary edema: The accumulation of fluid in the lungs
  
• Retinopathy: Changes in vision due to the rupture of blood vessels servicing the retina (the part of the eye that senses light)
• Stroke: Including hemorrhagic stroke caused by the rupture of a blood vessel in the brain
  
  

Tests and Other Tools to Diagnose Hypertensive Chronic Kidney Disease

Renal hypertension can be diagnosed with a combination of a physical exam, lab tests, and a review of your medical history. Based on the findings, other tests may be ordered to pinpoint the underlying cause.

Physical Exam

People with mild to moderate CKD are often asymptomatic. However, if the disease is advanced, a person may show signs of cachexia (wasting), periorbital edema (swelling around the eye), and peripheral edema (swelling of the legs, ankles, and feet). They may also report tiredness, shortness of breath with normal activity, decreased urine output.

The exam will also involve a stethoscope to listen for abdominal sounds, called bruits, that are caused by obstructed or turbulent blood flow. In people with renal artery stenosis, a whooshing sound will often be heard when a stethoscope is placed over the kidneys.

Lab Tests

Blood and urine tests can provide evidence of renal hypertension. These typically include:

• Albumin test: A blood test that measures the amount of a protein, called albumin, that can accumulate when the kidneys are malfunctioning
• Blood urea nitrogen (BUN): A blood test that measures the amount of nitrogen-containing ammonia that can also accumulate when the kidneys are not working
• Creatinine tests: Blood and urine tests that both measure the amount of a waste product called creatinine that is normally expelled from the body in urine
• Estimated glomerular filtration rate (eGFR): A calculation of how effective the filters of the kidneys are working based on the creatinine levels in the blood
• Lipid panel: A series of blood tests that measure the amount and percentage of cholesterol and triglycerides in the bloodstream
• Urinalysis: A comprehensive analysis that checks for abnormalities in urine, including the presence of blood and high protein levels

Imaging Tests

Imaging tests are used to diagnose and characterize renal artery stenosis in people with CKD. The types of tools used may include:

• Duplex ultrasound: An non-invasive device that can visualize the renal arteries using reflected sound waves
• Computed tomography (CT): A technology that creates cross-sectional X-ray images of the renal arteries, typically with the aid of a contrast dye injected into a vein
• Magnetic resonance angiography (MRA): An imaging tool, also used with a contrast dye, that visualizes blood vessels of the kidneys using powerful magnetic and radio waves
• Renal arteriography: A type of X-ray in which contrast dye is injected directly into the renal artery to identify areas of obstruction

Treating Hypertensive Chronic Kidney Disease

The treatment of renal hypertension can vary based on the severity of renal artery stenosis and other factors. This may involve lifestyle changes, medications to reduce blood pressure, and specialist procedures that improve blood flow to the kidneys.

If left untreated, renal hypertension can accelerate the progression of CKD and lead to end-stage renal disease.

Lifestyle Changes

If renal hypertension is diagnosed, lifestyle changes alone will not be enough to slow the progression of the disease. They can, however, modify or eliminate some of the risk factors that contribute to high blood pressure and CKD.

Among some of the lifestyle changes that can significantly improve outcomes in people with renal hypertension are:

• Quitting cigarettes
• Achieving and maintaining an ideal weight
• Eating a healthy, low-fat diet (including the appropriate restriction on protein)
• Reducing your salt intake
• Exercising regularly
• Limiting alcohol consumption

Medications for Renal Hypertension

The American College of Cardiology (ACC) and the American Heart Association (AHA) recommend antihypertensive medications as the first-line therapy for renal hypertension. These drugs bring down blood pressure in different ways and help prevent further plaque buildup in arteries.

The ACC/AHA classifies the following two drugs as preferred, first-line agents:

• ACE inhibitors: A class of oral drugs that reduces blood pressure by blocking an enzyme known as angiotensin II
• Angiotensin receptor blockers (ARBs): A class of oral drugs that prevent angiotensin II from attaching to receptors in the heart, blood vessels, and kidneys

Other drug options that can help lower blood pressure in people with renal hypertension include calcium channel blockers, thiazides diuretics ("water pills"), beta-blockers, and Dralzine (hydralazine).

Specialist Procedures for Renal Hypertension

There are no drugs that can reverse renal artery stenosis. If the obstruction of blood flow to the kidneys is significant, certain procedures may be recommended.

These procedures are generally considered when a person fails to respond to medications alone, cannot tolerate medications, or has unexplained pulmonary edema, congestive heart failure, or unstable angina.

The specialist procedures commonly used to treat renal hypertension include:

• Renal angioplasty and stenting: A minimally invasive procedure in which a flexible tube called a balloon catheter is fed into the renal artery to inflate it, after which a short piece of tube called a stent is placed inside the vessel to keep it open
• Renal artery bypass surgery: A type of surgery in which a blood vessel from another part of the body is grafted into the area of blockage to restore blood flow

Coping With Hypertensive Chronic Kidney Disease

If you have been diagnosed with renal hypertension, there are things you can do to better cope with treatment. This includes seeing your kidney specialist regularly to monitor your kidney function and ensuring that all other chronic medical conditions you have are properly managed.

Here are some other ways to improve your well-being and quality of life if you have renal hypertension:

• Learn what your routine blood tests mean. This allows you to make informed decisions about your health and understand what lifestyle adjustments you need to make to improve your results. Studies have shown that health literacy has a positive impact on health outcomes in people living with kidney disease.
• Manage your diabetes. Around 1 in 3 people with renal artery stenosis have diabetes. Diabetes, in turn, complicates kidney disease by promoting the formation of plaque. If you are struggling to control your diabetes, speak with a specialist about ways to improve or adjust your diabetes treatment.
• Reduce stress. Chronic stress is closely linked to high blood pressure. Finding ways to reduce stress can enhance the effects of antihypertensive drugs you are taking. Strategies include routine exercise, practicing mind-body therapies like yoga or meditation, and joining a support group to interact with others living with CKD.

Summary

Renal hypertension is high blood pressure caused by damage to the kidneys. It is a condition that can occur in people with chronic kidney disease when the arteries servicing the kidneys become narrow and hardened (referred to as renal artery stenosis). Atherosclerosis is the most common cause of this.

Renal hypertension tends to affect people over 65, particularly those who smoke or are overweight. There may be few if any symptoms in the early stages. But, as the blood flow to the kidneys is progressively reduced, a cascade of symptoms—from nausea and low urine output to confusion and irregular heartbeat—can develop.

Renal hypertension can be diagnosed with a physical exam, blood and urine tests, imaging studies, and a review of your medical history. The first-line treatment is antihypertensive drugs like ACE inhibitors and angiotensin receptor blockers (ARBs).

For those whose condition is progressing despite medications, specialist procedures like balloon angioplasty or renal artery bypass surgery may be recommended.

A Word From Verywell

It can be distressing to learn that you have chronic kidney disease or to hear that your condition is progressing despite treatment. The most important thing to remember is that CKD has no set course and that the disease can vary from one person to the next. Some people can live for many years with CKD and never progress to kidney failure.

By taking control of your condition—by making necessary lifestyle changes and taking your medications as prescribed—you can begin to normalize CKD in your life and reduce the daily stresses that can undermine both your health and quality of life.

This includes educating your family and friends so that they understand what CKD is, why certain lifestyle changes are needed, and what they can do to best support you.