You probably know that high blood pressure can be bad for your health, but do you know how exactly it affects your organs? Read on to learn more about how high blood pressure can affect your kidneys, how kidney function is related to blood pressure and much more
Hypertension is known as “the silent killer”, and there is a very good reason for that moniker. Along with increasing your risk for cardiovascular diseases, and stroke, high blood pressure can also damage your kidneys, eyes, and brain. In this article, we will focus on blood pressure and kidney disorders; how your kidneys control your blood pressure, the effects of hypertension on kidneys, and how to treat and prevent hypertensive kidney damage.
Understanding the Connection Between Blood Pressure and Kidneys
The kidneys play an important role in removing waste products from the body and in controlling your blood pressure levels through the Renin-Angiotensin-Aldosterone System (RAAS). The kidneys control blood pressure by removing water and salt from blood and producing hormones that help in controlling blood pressure.
Uncontrolled high blood pressure can make your blood vessels narrower. As a result, there is a lack of sufficient blood, and hence oxygen and nutrients for the kidney cells. This leads to scarring of kidney tissue and reduced functioning of the kidneys.
Damaged kidneys lose the ability to filter blood and regulate the fluid, hormones, and salts in the body. Eventually, the kidneys fail to regulate blood pressure.
Can Blood Pressure Cause Kidney Damage?
Hypertension is the second leading cause of the development of kidney damage and kidney failure. Uncontrolled high blood pressure can make your blood vessels narrower. As a result, there is a lack of sufficient blood, and hence oxygen and nutrients for the kidney cells. This leads to scarring of kidney tissue and/or conditions like chronic kidney disease (CKD), where the functioning of the kidneys is reduced.
High blood pressure can also damage the small and delicate blood vessels present in and around your kidneys, leading to leakage of fluid and proteins like albumin from the blood vessels into your urine. Damage to the blood vessels that filter the blood in your kidneys can also result in the retention of substances that need to be eliminated, like creatinine and urea. This results in increased serum or blood creatinine levels, high blood urea levels, and the accumulation of waste and toxins in your body. High urea in blood causes complications like seizures, fainting, heart attack, and kidney failure when left untreated.
CKD can be divided into five stages based on the extent of damage and deterioration of kidney function, particularly the glomerular filtration rate (your kidney’s capacity to filter blood). If left untreated, hypertension can cause CKD to worsen, resulting in kidney failure, which is also known as end-stage kidney disease (ESKD).
The following table shows the classification of different stages of CKD based on the glomerular filtration rate.
|Stage of CKD
|Stage 1 – Mild kidney damage with normal kidney function
|>90 mL/min/1.73 m²
|Stage 2 – Mild kidney damage with slightly reduced kidney function
|60 to 89 mL/min/1.73 m²
|Stage 3A – Mild to moderate loss of kidney function with kidney damage
|45 to 59 mL/min/1.73 m²
|Stage 3B – Moderate to severe loss of kidney function with kidney damage
|30 to 44 mL/min/1.73 m²
|Stage 4 – Severe loss of kidney function with kidney damage
|15 to 29 mL/min/1.73 m²
|Stage 5 – End Stage Renal Disease (ESRD) or kidney failure
|<15 mL/min/1.73 m²
Source: The National Kidney Foundation USA
Can Kidney Disorders Cause Hypertension?
When your kidneys are damaged due to conditions like Type 2 Diabetes or infections, it can lead to the accumulation of waste like urea and the retention of sodium and water in your body. This can lead to an increase in your blood volume, which increases the tension in your blood vessels, thus raising your blood pressure.
Also, when the arteries that supply blood to your kidneys are damaged, it can reduce the blood flow to your kidneys. Your kidneys perceive this reduction in blood flow as caused by poor circulation resulting from low blood pressure, which causes them to retain more sodium and water in order to raise your blood pressure levels. This further elevates your already high blood pressure levels. Hypertension caused by chronic kidney disease is called renal hypertension.
How are Kidney Disease and Hypertension Treated?
Your treatment for chronic kidney disease will be based on the stage of CKD you would be diagnosed with. When you have CKD and Hypertension, your treatment will include:
- Lowering your blood pressure to below 130/80 mmHg or a target determined by your physician.
- Keeping your glycosylated haemoglobin (HbA1c) levels below 6.5% (even if you do or do not have Type 2 Diabetes).
- Lowering your total cholesterol levels to below 200 mg/dl.
- Preventing the progression of your kidney disease.
- Lowering your risk for cardiovascular diseases.
- Lowering your sodium intake to below 2300 mg per day (preferably to 1500 mg).
Your physician may prescribe anti-hypertensive medications along with other medications to prevent the elevation in your blood pressure that is triggered by your kidneys.
Your doctor may recommend dialysis or kidney transplant if you are experiencing kidney failure or if your kidney function is severely compromised.
How Can You Prevent Kidney Damage Caused by Hypertension?
If you have hypertension, you can take the following measures to prevent complications like kidney damage.
- Make sure that you are taking all your medications and following your treatment plan.
- Maintain target blood pressure, blood sugar, and cholesterol levels.
- Lose weight if you are overweight (body mass index over 25 kg/m²).
- Get at least 30 minutes of moderate-intensity exercise every day.
- Sleep for at least 7 to 9 hours every night.
- Follow a low sodium or DASH (dietary approaches to stop hypertension) diet and avoid overly processed and salty foods.
- Limit or avoid alcohol consumption.
- Quit smoking if you are a smoker.
- Learn to relieve or manage stress in healthy ways.
When to See a Doctor?
If you have hypertension, consult your doctor if you are experiencing any of the following symptoms of CKD.
- Increased or decreased frequency of urination
- Weakness or fatigue
- Oedema or swelling in your limbs, especially legs
- Muscle cramps and aches
- Loss of appetite
- Nausea and/or vomiting
- Insomnia or trouble sleeping
- Rashes or itchy and dry skin
- Trouble concentrating or experiencing confusion
Don’t Have Time To Read?
- An important organ responsible for maintaining blood pressure is your kidney. Your kidneys maintain your blood pressure and the fluid balance in your body through the Renin Angiotensin Aldosterone System (RAAS).
- High blood pressure can damage the blood vessels in and around your kidneys, thus cutting off their blood flow and the supply of oxygen and nutrients, which can lead to a loss of kidney function and kidney damage.
- When you have kidney disorders like chronic kidney disease (CKD), your kidneys are unable to function efficiently, which results in the accumulation of waste products in your body, which further raises your blood pressure.
- Chronic kidney disease can be classified into five stages based on the functioning of your kidneys, the last stage of which is kidney failure.
- The treatment for CKD depends on the stage you are in and includes lowering your blood pressure levels, along with your blood sugar and cholesterol levels.
- You can prevent or slow down CKD by following your treatment plan strictly, maintaining a healthy weight, exercising regularly, following a low sodium or DASH diet, getting better sleep, and cutting out alcohol and smoking.
- You should consult a physician if you are experiencing any symptoms of impaired kidney function like nausea, vomiting, insomnia, skin rashes, fatigue, muscle cramps, increased or decreased frequency of urination, etc.
- Use the Phable Care App to consult India’s leading cardiologists, order medicines, book lab tests, integrate BP monitors and other devices to get real-time remote care from the comfort of your home. Also, check out our Hypertension Management Program which provides 360º care. Let’s treat low/high blood pressure problems together.
Friendly Asked Questions
Uncontrolled and untreated high blood pressure can damage your kidneys over a period of several years. However, if your blood pressure is extremely high and if you have other chronic conditions like Type 2 Diabetes, you can observe some form of kidney damage within months.
Yes, if your kidneys are not functioning properly, they would be unable to filter out and excrete excess salts and water from your body. The retention of sodium and water can lead to an increase in your blood pressure.
Yes, some studies have found that frequent urination, especially at night, can be a sign of uncontrolled hypertension. Excessive salt intake and some high blood pressure medication like diuretics can also cause frequent urination.
Yes, kidney stones can affect the functioning of your kidneys, leading to sodium and water retention. This can cause elevated blood pressure levels.
If you are able to catch hypertensive kidney disease in its earliest stages, it can be reversed by controlling your blood pressure levels. However, it is impossible to reverse damage caused by kidney disease once it has progressed to more advanced stages.
Yes, lowering your blood pressure levels can halt the progression of kidney disease and preserve or improve kidney function.