When people develop kidney disease, either from an accident, kidney transplant, cancer, or an organic functional decline, their doctor may ask them to check their blood pressure, or may put them on blood pressure medication even when their blood pressure is normal. The reason why is often hard to explain. Here we will examine what the kidneys and high blood pressure do to each other, and why keeping blood pressure controlled is key.
High blood pressure is the leading chronic disease that could be preventable or modifiable. It is a potential cause for kidney disease and kidney failure, but is also a very common result in patients with Chronic Kidney Disease, including kidney transplant recipients. What that means is simply:
Kidney disease can cause high blood pressure, and high blood pressure can also cause kidney disease. You should take care of both.
High blood pressure can cause kidney damage. The kidneys have a lot of fragile blood vessels and filters to process and filter the blood and create urine. When blood pressure is high, it leads to narrowing and damage to veins and arteries, including in the kidneys. This can cause the kidneys to lose blood flow, and get permanently damaged.
Kidney damage can cause high blood pressure. When the kidneys are damaged, all those fragile filters may get broken or blocked. This can cause all the blood that should filter through the kidneys to get backed up behind them, like a traffic jam, and cause blood pressure in arteries and other organs to rise.
The National Kidney Foundation, based on several SPRINT trials and the ACCORD-BP trial, have recently updated their guidelines on the target blood pressure range for patients with Kidney Disease.
The recommendation is now to keep systolic blood pressure below 120 mmHg to reduce the risk of cardiovascular disease and death. While the previous recommendations were to keep it either below 130, or below 140 depending on the trials, the new position statement from the National Kidney Foundation stresses the importance of intense management of blood pressure, recommending patients follow this trifecta of healthy living to keep blood pressure in normal range:
If your blood pressure is and always has been normal, just keep an eye on it. Blood pressure tends to bounce around a lot, so most people that check it once per week are actually not checking often enough. iHealth Unified Care recommends that you check at least 4-5 times per week if your blood pressure is well-controlled. Double-check with your doctor about how often you need to check it.
Since home monitors are never 100% perfect in detecting true blood pressure, and since blood pressure tends to bounce around so much, the best practices for taking a measurement, per the American Heart Association, are to re-measure blood pressure 3 times in a row to get an accurate average.
Each time you measure, take two or three readings to make sure your results are accurate.
If you have blood pressure that is high, we, along with the Mayo Clinic and American Heart Association, recommend measuring your blood pressure twice daily. The first measurement should be in the morning before eating or taking any medications, and the second in the evening. Your doctor might recommend taking your blood pressure at the same time each day.
While you should be watching your blood pressure if you have kidney disease, knowing why and how often to check it can be confusing. Remember that kidney disease and high blood pressure together can not only further damage the kidneys, but increase your risk for heart disease and also death. For a long-lasting, comfortable life, take medications regularly, eat healthfully, and exercise to keep your blood pressure under 120/80. Home blood pressure monitoring is not a substitute for visits to your doctor, and home blood pressure monitors may have some limitations. Even if you get normal readings, don't stop or change your medications or alter your diet without talking to your doctor first. To know how you can balance your diet for kidney disease together with other diets for blood pressure and glucose, talk with your Dietitian for great ideas.