Comorbidites: Chronic Kidney Disease

Heart failure (HF) or chronic kidney disease (CKD), which comes first? The answer is either. Heart disease can cause kidney disease and kidney disease can cause heart disease.^1-2 The heart and kidneys work closely together.²

As the population ages, there has been a rise in the incidence (rate of occurrence of new cases) and prevalence (actual number of cases during any specified time period) of people with heart failure and kidney disease. Besides age, other risk factors for developing HF and CKD include hypertension, diabetes mellitus, or other cardiovascular and kidney disease risk factors.³

People who have both conditions, called comorbidities, are at increased risk for complications, multiple hospitalizations, and the potential need for more intensive treatments.³

Heart failure

The heart does not pump blood effectively in people with heart failure. This means the heart has to work harder to pump the circulating blood. As a result, the blood can back up and cause fluid retention, swelling in your legs, ankles, feet, and other tissues in your body. This can affect the kidneys because if they don’t get enough blood flow, they may have trouble eliminating excess fluid and filtering waste.⁴

Chronic kidney disease

The job of the kidneys is to filter waste from the body.⁴ The kidneys rely on the circulatory system to move blood throughout the body collecting waste and extra fluid that will eventually be excreted as urine. If the kidneys are damaged, the filtration system doesn’t work properly, and waste can build up in the body. As kidney function is lost it is called chronic kidney disease.⁴

Like heart failure, symptoms of CKD may not be recognized before the condition is advanced.⁴ Some people start to feel sick or tired all the time. A doctor will perform blood and urine tests to determine the presence of kidney disease.^2-4 The blood tests measure GFR, glomerular filtration rate, which measures how well the kidneys are filtering the blood. The urine test checks for the presence of albumin in the urine. Albumin is a protein that can escape into the urine when there is kidney damage.⁴ It is a sign of reduced kidney function.

Kidney failure is the term used to define the stage where your kidneys are no longer working and the body requires dialysis, a process where the blood is filtered by machines or a kidney transplant.⁴

Relationship between kidney and heart disease

HF and CKD share several common causes including diabetes (insert HU link) and high blood pressure.^2,4 Diabetics have too much glucose, blood sugar, in their blood. (insert link to HU diabetes) Over time, elevated sugar levels can cause damage to vital organ functions including the heart and kidneys.⁴

Blood pressure describes the force of blood as it pushes against the walls of your blood vessels during circulation.⁴ When blood pressure is elevated, the heart has to work harder to pump blood out into the body. This strain can cause blood vessel damage including to the small blood vessels in the kidneys. This can impair kidney function, interfering with the filtration of blood and the elimination of excess salt and water from the body.⁴

High blood pressure is considered a contributing cause of kidney disease and kidney disease is also a recognized cause of high blood pressure. Like with HF, it creates a cycle that can cause each disease to make the other worse.^2,4

People with CKD are monitored for any signs of heart disease, as heart disease is the most common cause of death among people on dialysis.² Your healthcare team may make recommendations on medications and lifestyle. Controlling blood glucose and blood pressure levels with diet and exercise regimens can help your body maintain function along with any prescribed medications.⁴ Always check with your doctor before making any changes. Some general tips include:

• Maintain blood pressure, blood glucose and cholesterol levels
• Stay active and exercise
• Watch your weight
• Eat healthy foods including fruits, vegetables, whole grains, low-fat and low-sodium foods

Conclusions

The strategies for treating HF are generally the same in patients with or without CKD.³ But the presence of CKD does require special considerations; the control of fluid overload, targeted use of medications, possible dialysis, and the cooperation of medical specialists.³

Researchers continue to examine the correlation between the two conditions. This will help to define improved strategies for the identification, prevention, diagnosis, and management of both heart failure and chronic kidney disease.³