High blood pressure, often referred to as hypertension, is a major health concern that can cause a multitude of complications. Among these complications, one of the most severe outcomes is the damage it can cause to your kidneys, potentially leading to kidney failure. When blood pressure increases, it adds strain to the tiny blood vessels within the kidneys which, over time, can cause deterioration.

The kidneys are a pair of bean-shaped organs that play a pivotal role in filtering waste products and excess fluids from the blood to be excreted in urine. They also regulate vital functions such as electrolyte balance, blood pressure regulation, and red blood cell production. Hypertension can damage the blood vessels leading to and within the kidneys, impairing their ability to function effectively. 

The kidneys are sophisticated filtering systems that remove waste products and excess fluid from the bloodstream, producing urine. Each kidney contains around a million filtering units called nephrons. Each nephron has a glomerulus—a tiny blood-filtering vessel—and a tubule, which collects the filtered urine. The kidneys also regulate various body functions, including blood pressure, electrolyte balance, and red blood cell production.

In order to understand high blood pressure, we need to identify the key role of the circulatory system when it comes to the regulation of our blood flow. The root cause of high blood pressure often stems from irregularities within this system. High blood pressure, also known as hypertension, can result from various factors – a poor diet, a lack of exercise, family history of high blood pressure, etc. However, it’s when our blood circulates at unusually high pressure in the blood vessels of our circulatory system that we see problems arise.

In essence, the circulatory system moves blood throughout the body and back to the heart; it is responsible for the transportation of nutrients, hormones, and gases like oxygen and carbon dioxide. When blood pressure is high, it means that the blood is moving through our arteries more forcefully than it should, which can cause high blood pressure and, over time, lead to damage, and over a long period of time, it can lead to kidney failure. 

When blood pressure is high, the increased force can weaken and narrow the renal arteries. Over time, this can lead to arteriosclerosis, where the arteries become thickened and stiff, restricting blood flow to the kidney tissue. The nephrons, or filtering units, require a constant supply of oxygen-rich blood. Without it, they begin to lose their filtering ability. As the condition progresses, this can lead to chronic kidney disease (CKD), which may culminate in kidney failure, also known as end-stage renal disease (ESRD)

Diagnosing high blood pressure and kidney disease is a step-by-step process for health care professionals. Initially, a doctor will perform a physical examination and review the patient’s health history. This is the first step in evaluating if the patient’s high blood pressure might lead to kidney disease. Blood tests and urine tests are conducted to monitor the patient’s disease status.  The proper care of people with high blood pressure is important to prevent potential complications like kidney disease. In the case of prolonged and untreated high blood pressure, the risk of kidney disease increases. Doctors play an essential role in providing care and managing the disease. Through consistent care, doctors can help control high blood pressure and prevent further kidney disease occurrence.

Rarely, instead of being a sequel of hypertension, kidney disease may be the cause of secondary hypertension. In the condition renal artery stenosis, the blood vessels that supply blood to the kidneys are narrowed. This results in the damage of kidney cells over time as they do not receive adequate oxygen and blood supply. Over time, the kidneys lose the ability to remove excess water, leading to increased extracellular volume which then causes an increased blood pressure. 

Renal artery stenosis can be caused by the build-up of cholesterol deposits in the kidney arteries. This is common in patients with hyperlipidaemia. 

As such, it is important to seek help from your health care provider to make the proper diagnosis of essential hypertension or secondary hypertension as well as check on your kidney health, and control other risk factors such as hyperlipidaemia. 

The health implications of high blood pressure can be profound, particularly when considering the kidneys’ role in managing this condition. There are many components that contribute to our blood pressure. The following is the equation for blood pressure which shows the link between heart rate, circulatory volume and blood vessel tone.

Blood pressure = heart rate x stroke volume x systemic vascular resistance

Stroke volume refers to the volume of blood pumped out of the heart into the aorta every heart beat, while systemic vascular resistance refers to how much resistance there is to blood entering the artery. Typically, if an artery is narrow, there is more resistance.

As our kidneys are responsible for removing excess fluid from our body, damage to our kidneys means that excess fluid does not get removed as well as before. Since the volume of blood is an important component of blood pressure, the excess fluid that the kidneys do not remove contribute to even higher blood pressure, causing a vicious cycle between high blood pressure and kidney damage. 

Simultaneously, damage to the kidneys also impair its ability to filter and maintain electrolytes concentration properly. Patients with chronic kidney disease are prone to hyperkalaemia (high potassium levels). When potassium levels reach a critical level, they can cause the heart to pump irregularly and even death due to an arrhythymia. 

If you’ve been diagnosed with high blood pressure, it’s crucial to understand the impact that can have on your body, especially your kidneys. High blood pressure can cause significant damage to these vital organs. Often, the damage isn’t noticeable because kidneys can still function with minimal damage, so many people are not aware that their high blood pressure is harming their kidneys. Over time, however, the continuous strain high blood pressure puts on the kidneys can lead to extreme damage.

The kidneys play a significant role in the overall health balance. They’re responsible for removing waste from our body, so when they don’t work as they should, it leads to a toxic build-up. That’s when symptoms of kidney disease show up. These symptoms may include swelling of both feet, fluid in the lungs, decreased ability to think due to uremia. 

It’s often wondered if the damage from high blood pressure can be reversed, specifically asking, can kidneys heal from the onslaught of this condition? Other than having a kidney transplant, chronic kidney disease is not reversible. A kidney transplant is also not readily available to everyone as it depends if a suitable donor can be found. As the nephrons get damaged by high blood pressure, the body is not capable of healing this damage or create new nephrons to replace the damaged ones. However, it is possible to impede further deterioration of chronic kidney disease by controlling high blood pressure. 

The following table shows the stages of chronic kidney disease. When a patient reaches end stage kidney disease, they will require dialysis daily or three times a week to remove the toxins from their blood stream and to ensure that the electrolytes in their blood stays a healthy level.

When people reach end stage renal disease, they will require haemodialaysis at least three times a week or peritoneal dialysis to remove the waste products from their blood. 

Preventing kidney disease involves making various essential lifestyle changes designed to manage blood pressure, promoting overall health. Firstly, adopting a healthy diet such as the DASH diet can help maintain blood pressure levels. If you wish to learn more about the DASH diet, you can visit our diet for patients with hypertension page. Alternatively, you may approach the nurse or other members of your healthcare team to find out more about healthy eating. Additionally, incorporating regular physical activity into your routine can also contribute to preventing kidney disease and maintaining healthy blood pressure.

Limiting alcohol intake and quitting smoking are other critical steps in managing blood pressure and preventing kidney disease. Regular health check-ups are crucial in early detection and management of high blood pressure, which, if left untreated, can lead to kidney disease. Prevention is always better than cure, so it’s essential to adopt a healthy lifestyle to manage blood pressure and reduce the risk of kidney disease.

The following table shows the stages of chronic kidney disease. When a patient reaches end stage kidney disease, they will require dialysis daily or three times a week to remove the toxins from their blood stream and to ensure that the electrolytes in their blood stays a healthy level.

When people reach end stage renal disease, they will require haemodialaysis at least three times a week or peritoneal dialysis to remove the waste products from their blood.

Looking ahead at future directions, clinical trials are shaping the way health care professionals manage kidney disease, an increasingly recognized complication of high blood pressure. Clinical trials continue to evolve, yielding innovative and promising solutions for the care of high blood pressure caused kidney disease. In these trials, health care providers explore new ways to treat kidney disease, emphasizing the significance of effective care. These trials are crucial as high blood pressure continues to be a leading cause of kidney diseases, and it’s only through this form of research that we can create more effective care strategies.

In a study published in the New England Journal of Medicine in November 2022,  a phase 2 trial focuses on baxdrostat, a drug targeting aldosterone synthase, for treating treatment-resistant hypertension. In a placebo-controlled trial, patients with hypertension unresponsive to at least three antihypertensive agents, including a diuretic, were given baxdrostat. Results showed dose-dependent reductions in systolic blood pressure, with the highest dose group showing a significant reduction compared to placebo. The drug was well-tolerated with no serious adverse events or instances of adrenocortical insufficiency. 

High blood pressure can not only cause damage to kidneys but also can be one of the many causes of heart attacks, and strokes. As hypertension typically does not cause symptoms, it may not be easily picked up by yourself. Renal damage can cause symptoms such as swelling in both legs, difficulties in breathing, proteinuria. Having a family history of high blood pressure predisposes one to hypertension. While it is possible to control blood pressure with lifestyle changes such as adhering strictly to the DASH diet, it is still important to consider therapy if one’s blood pressure cannot be adequately controlled with these methods. Your doctor may choose to start you on hypertensive medications such as ACE inhibitor to control your blood pressure. To prevent further deterioration of chronic kidney disease caused by high blood pressure, it is important to maintain a normal blood pressure. 

Disclaimer: No content on this site should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.