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.
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.
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||GFR|
|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
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.
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:
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.
If you have hypertension, you can take the following measures to prevent complications like kidney damage.
If you have hypertension, consult your doctor if you are experiencing any of the following symptoms of CKD.
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