Does High Blood Pressure Affect Your Kidneys?

Progressive high blood pressure may result in significant organ damage¹, including your brain, kidneys, heart, and eyes. Worsening blood pressure in your kidneys can cause conditions such as:

• Kidney failure

• Kidney artery aneurysm

• Kidney scarring

However, proper blood pressure management can reverse kidney damage² and improve your health. Keep reading to learn how.

What is high blood pressure?

Blood pressure measures the pressure of blood pumped by the heart pressing against the walls of your blood vessels. Normal blood pressure³ for most adults is less than 120/80mm Hg. High blood pressure is common, affecting over 100 million American adults⁴. While high blood pressure affects different age groups, it is most prevalent in people above 65 years⁵.

The following factors may cause high blood pressure:

• Obesity

• Stress

• Pregnancy

• Pre-existing health conditions like kidney diseases

• Excessive alcohol consumption

• Unhealthy diet

• High sodium intake

• Genetics

• Certain hormonal conditions

• Untreated sleep apnea 

What role do the kidneys play?

Kidneys are bean-shaped organs located in the abdomen. The kidney performs various essential functions, including:

• Waste and toxin removal in the form of urine

• Salt or electrolyte balance in the body

• Releasing vital hormones that control blood pressure

• Releasing hormones that stimulate the bone marrow to create red blood cells

How does high blood pressure affect the kidneys?

Hypertension may cause the narrowing of blood vessels, reducing blood and oxygen supply to the kidneys. An adequate supply of nutrients and blood is a basic necessity for proper kidney functioning. Therefore, reduced blood supply results in reduced kidney function, progressive renal damage, and the development of some of the following conditions.

Kidney failure

Kidney failure is a progressive condition that involves the gradual loss of kidney function. One of the major causes of kidney failure is high blood pressure. Over time, untreated high blood pressure impairs kidney functioning, resulting in kidney failure.

The part of the kidney that is damaged by high blood pressure is known as the glomerulus. When the glomerulus is damaged, its filtration capacity is lowered, and a protein known as albumin filters into the urine. The appearance of this protein in the urine is one of the tests healthcare providers use to determine kidney disease.

A common symptom of kidney failure is swelling of the legs and feet because extra fluid is not being eliminated from the body. However, this may present as a symptom late in the development of the disease. That is why it is essential to see your doctor for regular check-ups to catch issues early.

High blood pressure may also be a sign of underlying kidney disease instead of being the primary cause. 

Kidney artery aneurysm

An aneurysm refers to the abnormal bulging of the blood vessel walls. High blood pressure causes a weakened kidney artery to bulge, resulting in a renal artery aneurysm.

Kidney scarring

Kidney scarring, also referred to as glomerulosclerosis, is kidney damage, particularly the scarring or hardening of the glomerulus. This condition occurs due to the decreased ability of the kidney to filter waste and toxins, resulting in waste accumulation within the body. Untreated kidney scarring can further progress to kidney failure due to additional damage to other kidney structures and loss of renal function.

What is chronic kidney disease?

Chronic kidney disease is a group of disorders that affects the proper function of the kidneys due to the excessive damage caused to your kidneys, and there are various causes.

Approximately 37 million adults⁶ in the US may have chronic kidney diseases, further increasing their risk of developing high blood pressure.

Various factors increase your risk of kidney disease, including:

• Age — The older you are, the higher your risk of chronic kidney disease as it most commonly affects those over 65. 

• Family history⁷ — Some patients are genetically predisposed to developing kidney disease if renal failure is shared among their family members.

• Diabetes — Patients with diabetes have an increased risk⁸ of developing kidney disease because their high blood glucose levels may damage kidney blood vessels.

• Obesity — Being overweight increases your risk of kidney disease.

• Hypertension — The higher your blood pressure, the higher the negative impact on kidney function.

• Ethnicity — Chronic kidney disease more commonly affects Black Americans and people of South Asian origin⁹.

Other common causes of kidney disease

Diabetes

Diabetes has a significant effect on the kidney's filtration system due to uncontrolled blood sugar levels. High blood sugar also destroys blood vessels supplying the kidney, reducing blood supply to the kidney and impacting functioning.

Autoimmune diseases

Some autoimmune diseases lead to the development of kidney disease, including:

• IgA nephropathy (Berger's syndrome) — When IgA antibody deposits accumulate in the kidney, this can cause kidney damage and inflammation.

• Goodpasture's syndrome — The destruction of the glomerulus of the kidney when antibodies mistake normal kidney tissue for foreign tissue and attack the kidney.

• Granulomatosis (Wegener's disease) — A type of vasculitis (blood vessel inflammation) that results in rapid kidney failure and other organ dysfunction. It often manifests as clusters of inflammatory cells or “granulomas” during a biopsy.

• Systemic lupus erythematosus — The body’s immune system attacks its organs, including the kidney. Systemic lupus erythematosus is also known as lupus.

Kidney infection

A kidney infection is a serious bacterial infection that may result in permanent kidney damage if not treated promptly.

Glomerulonephritis

Glomerulonephritis refers to the inflammation of the glomerulus, which is one of the most important structures of the kidney and is often linked to autoimmune diseases.

Congenital kidney conditions

Congenital kidney conditions such as polycystic kidney disease, where multiple cysts develop within your kidneys, can reduce kidney function over time. Intense kidney damage can affect your general health and can result in complications¹⁰ which include:

• High blood pressure

• Weak bones

• Nerve damage

• Anemia

• Poor nutritional health

• Increased risk of heart disease

• Increased risk of stroke

• Kidney failure, when kidney disease progresses to an irreversible stage

Can kidney disease cause hypertension?

The answer is yes. One of the kidney's vital functions is maintaining normal blood pressure¹¹ through a hormone known as aldosterone.

Kidney damage caused by kidney disease reduces your kidney’s ability to effectively control blood pressure, causing your blood pressure levels to spiral out of control. The uncontrollable rise in blood pressure causes further damage to the kidney by decreasing its blood supply, worsening the underlying kidney disease. This cycle continues, causing progressive deterioration of your health.

Hypertension can be categorized as either essential hypertension or secondary hypertension. Secondary hypertension refers to increased blood pressure due to an underlying medical condition, such as kidney or heart disease, tumors, a hormonal imbalance, or certain medications. Chronic kidney disease is the most common cause of secondary hypertension.

Is kidney damage from high blood pressure reversible?

You can reverse kidney damage caused by high blood pressure by treating hypertension and maintaining normal blood pressure. However, you should note that significant damage and extensive loss of kidney function may be irreversible. Advanced kidney damage can only be treated with regular dialysis or a kidney transplant, and lowering your blood pressure will have little to no effect at this stage.

Common symptoms of kidney failure due to high blood pressure

High blood pressure and chronic kidney disease tend not to have any warning signs and symptoms in their early stages. However, as kidney disease advances, most people will notice swelling in their legs or sometimes in the face and hands — a condition known as edema. Edema is a result of fluid accumulation in the body due to the reduced ability of the kidney to remove excess fluid.

Other noticeable symptoms may include:

• Weight loss

• Headaches

• Drowsiness

• Loss of appetite or nausea

• Vomiting

• Muscle cramps

• Chest pain

• Increased or decreased frequency of urination

• Itchiness from the buildup of toxins in the kidney

Diagnosis

Since both conditions do not present early warning signs, the only way to confirm or rule out whether you have either condition is to undergo testing.

Blood pressure can be easily measured at home by yourself or by your doctor or other healthcare professional using a blood pressure cuff.

To diagnose kidney disease, you need to seek the help of a healthcare professional to perform tests, which include:

• Blood test to check glomerular filtration rate — This shows how well your kidneys filter blood.

• Urine test to check albumin levels in your urine — Albumin is a protein that is usually not filtered in the kidneys, so it should not be found in urine. If albumin is detected in your urine, it shows that your kidneys are damaged.

• Urine test to check for blood in your urine — This can also be an early sign that the kidneys are damaged.

Your doctor may also perform these additional tests:

• Ultrasound or CT scan — To evaluate the size of your kidney, presence of kidney stones, or a tumor.

• Biopsy — To diagnose specific kidney disease, assess the level of damage, and create an appropriate treatment plan.

Managing kidney disease from high blood pressure

Chronic kidney disease caused by high blood pressure is manageable by maintaining healthy, normal blood pressure. Making positive lifestyle changes can be more beneficial in preventing the progression of both kidney disease and high blood pressure than medical procedures.

During the early stages of kidney disease, you can reduce further damage by:

Reducing salt intake

Restricting the amount of salt you consume helps your kidneys control blood pressure better. High salt intake is known to cause an increase in blood pressure, so reducing your consumption can help lower blood pressure and reverse kidney damage.

Taking appropriate medication

Prescription medication can lower your blood pressure and simultaneously halt the progression of kidney disease. These medications include angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme (ACE) inhibitors.

Regular physical activity

Studies¹² have shown that engaging in regular physical activity can help reverse the loss of kidney function and damage. It is recommended that you do at least 30 minutes a day of moderate exercise to lower your blood pressure levels. This helps your blood and oxygen supply to the kidney return to normal, supporting healthy kidney functioning.

Some recommended physical activities include any exercises approved by your doctor, stretching, brisk walking, swimming, and more.

Managing stress levels

Stress is commonly known to cause high blood pressure, and it can lead to kidney damage. Therefore, lowering your stress levels can significantly reduce your blood pressure, which in turn can help reverse kidney damage.

Ways you can manage your stress levels include:

• Prioritizing relaxation

• Meditating and participating in yoga

• Getting enough quality sleep each night

• Consulting a counselor, family, or friends

• Taking time off for a vacation

Weight loss

Losing weight offers various health benefits, including lowering blood pressure and reversing renal damage.

Shedding some pounds reduces the burden on your heart, which lowers blood pressure in the blood vessels and improves blood and oxygen circulation to vital organs. This can help reverse kidney damage.

Weight loss also improves renal function, decreases the presence of protein in the urine, and improves the filtration rate of the glomerulus.

Quitting smoking

Smoking significantly exacerbates kidney damage and worsens high blood pressure¹³, as it slows blood supply to your kidneys, intensifying kidney damage. It is recommended that smokers with kidney disease quit smoking to lower their chances of further kidney damage, reduce the loss of kidney function, and keep blood pressure in check.

Maintaining a healthy diet

A healthy diet can help to slow the progression of kidney disease. Eliminate unhealthy foods and replace them with healthier options that help to improve kidney function. Many doctors recommend consulting a dietician to develop an appropriate meal plan to improve your health.

Healthy diet tips include the following:

• Reduce salt intake to manage blood pressure better.

• Eat the appropriate amount and type of protein to help improve kidney functionality.

• Limit saturated and trans fat intake to lower cholesterol levels to maintain blood pressure within the normal range.

Treating irreversible kidney damage

Unfortunately, you cannot treat irreversible kidney damage through lifestyle or dietary changes. It requires the intervention of medical procedures like:

Dialysis

This is a minimally invasive treatment option for people with stage IV or end-stage kidney disease. The procedure supports kidney functioning, such as removing accumulated waste and toxins from your body, lowering your blood pressure by eliminating excess fluids, and maintaining your electrolyte balance within normal ranges.

Dialysis aims to improve your quality of life if you suffer from end-stage kidney disease but is not curative.

Kidney transplant

A kidney transplant, also known as renal transplant, is an invasive surgical procedure in which a healthy functioning kidney from a compatible donor is implanted in your body. Typically, you will only undergo this procedure when your kidneys have lost up to 90% of their functionality¹⁴.

When to see a doctor

It's recommended to visit your doctor if:

• You notice some of the symptoms of advanced kidney disease, such as swelling in the legs and feet.

• Your blood pressure medication is ineffective in lowering your blood pressure. You should consult with your doctor to come up with other treatment plans.

• Your family is genetically predisposed to getting high blood pressure and kidney failure. If so, seek medical advice immediately to find out if you are vulnerable to developing either condition.

• Your blood pressure is constantly high despite having a healthy lifestyle.

The lowdown

Managing your blood pressure is important for maintaining healthy kidney functioning. A significant effect of high blood pressure, or hypertension, is kidney damage which reduces kidney functioning, including regulating blood pressure.

High blood pressure can cause kidney disease, and kidney disease can also cause secondary high blood pressure. When renal diseases alter kidney functions, the ability of the kidney to maintain blood pressure is reduced, resulting in a spike in blood pressure levels.

Fortunately, kidney diseases caused by hypertension are generally manageable, and kidney damage can be reversed over time.

 To prevent kidney disease or its progression, make sure to manage your blood pressure. You can lower your blood pressure through exercise, a healthy diet without excess salt, reducing stress, sleeping well, and quitting smoking.