On the surface, it can be hard to see how heart diseases and kidney diseases are related. In this article, we speak to our cardiologist Dr. Bernard Kwok and Renal Physician Dr. Loh Ping Tyug, to learn more about how the two major organs are interconnected.
To understand this, we must first look at the function of the heart and kidneys. They are both essential organs of the body that work in conjunction to keep us healthy. Just like how it takes two hands to clap, the relationship between the two is as such. Heart diseases can lead to kidney problems and kidney diseases can also lead to heart issues.
The cardiovascular system is made up of the heart and various blood vessels that help to pump oxygen-rich blood throughout the body to keep the cells alive. It acts as a delivery system to distribute nutrients and oxygen across the body.
On the other hand, kidneys filter your blood, removing wastes and extra water from the body and clean the blood while balancing the minerals in your body. Kidneys also help in regulating blood pressure and control the red blood cell production.
"Using the cardiorenal axis, it has proven that the heart and kidney are linked. Suppose there is a certain degree of heart problem or heart failure. In that case, the kidneys may not be receiving enough blood supply. The health of the kidneys will suffer as a result," explained Dr. Kwok.
Both heart and kidney diseases often share similar risk and causative factors such as high blood pressure, blood sugar, cholesterol and uric acid. According to Dr. Loh, a high blood pressure causing heart failure can also cause hypertentive kidney disease.
"Inside the kidney, there are many tiny kidney filters. If a patient has high blood pressure for a duration, these filters are damaged directly from the high pressure. In addition to that, high blood pressure also causes narrowing and blocking of the blood vessels; It causes scarring and the weakening of the muscle around the blood vessels; affecting the perfusion to the kidneys,” she explained.
"We are born with a finite number of kidney filters. Our kidneys do not generate new filters once they are damaged. Your kidney function decline when more kidney filters are damaged," Dr. Loh added.
Similarly, kidney diseases can affect heart health. Dr. Loh explained: "If a patient has chronic kidney disease with kidney failure caused by diabetes, this patient has a higher cardiovascular risk compared to someone without kidney disease.”
Dr. Kwok further advised that there is an interplay of many factors that could cause both organs to fail in an unlinked manner.
"One of these could be hormonal because both the kidneys and the heart produce certain hormones and these hormones can affect the function of the other organ. Hence, heart diseases may not necessarily be due to kidney failure."
"It is a complex interplay of factors such as hormonal factors, the dynamics of blood flow, or just simple circulation," he added.
"Kidney diseases can be detected with simple blood and urine tests. Most health screening packages these days will have both these tests included to detect kidney diseases. For most heart problems, the suspicion increases only when a patient starts presenting with symptoms," explained Dr. Kwok.
"There are several urine tests that can detect kidney damage, whereas more efforts are needed to detect early heart problems," he emphasized.
A key benefit that stemmed from the heart and kidney interdependence is that what is right for the heart is also good for the kidney.
"There are many good medications for the heart to minimize and reduce the adverse effect due to the narrowing of heart vessels and hence, help manage kidney diseases," Dr. Loh shared. However, it does not always go together.
"Certain medications can have a protective effect on both the heart and the kidneys. However, if we use certain medications to reduce blood pressure, the kidneys will suffer," Dr. Kwok explained.
Touching on the impact medications have on the kidneys, Dr. Loh said: "For older patients, the kidney reserves can be very little. As much as we want to do something better for the heart, but whatever we do, be it deciding the medication or changing the dose; it may disproportionately affect the kidneys.”
"The common tip heart and kidney patients should follow is avoiding a diet that is high in salt. High salt intake diet causes high blood pressure, a condition that can have a detrimental effect on both the heart and the kidneys. So one of the simplest things to do is to watch our diet," Dr. Kwok advised.
Dr. Loh echoed the same about watching the salt intake as it increase our blood pressure.
"It is very important to check the condition of your body regularly as you should not be taking the same blood pressure medications or dose for your lifetime. Instead, it should be in accordance with the status of your heart, kidney and other co-morbid conditions. You should take your medication regularly to keep blood pressure in control throughout the day," she added.
In conclusion, the heart and kidneys have a bidirectional relationship and the failure of one organ dysfunction the other.
