Cholesterol and Chronic Kidney Disease

Cardiovascular disease (CVD) is common in people with chronic kidney disease (CKD).  Many already have a diagnosis of cardiovascular disease prior to being diagnosed with chronic kidney disease. Cardiovascular disease is the leading cause of death in people with kidney  disease, regardless of the stage. It’s important to understand the risk factors for cardiovascular disease, especially the ones specific to chronic kidney disease. Find out what types of fats you should limit and cholesterols that are important to help you stay healthy and active.

Risk factors for cardiovascular disease (CVD)

High cholesterol levels have been linked to heart disease and stroke. For people without chronic kidney disease, risk factors for heart disease include:

• High total cholesterol
• High LDL cholesterol
• High triglycerides
• Low HDL cholesterol
• Older age
• Male
• High blood pressure
• Smoking
• Physical inactivity
• Obesity
• Diabetes
• Menopause
• Family history
• Left ventricular hypertrophy (LVH), or enlargement of the left side of the heart

Some of these risk factors, including smoking and blood pressure, can be controlled with lifestyle changes (quit smoking, monitor your blood pressure, eat right, exercise, etc.) or medicines, while the other factors, such as age or family history, are out of your control.

Risk factors for cardiovascular disease in people with kidney disease

Some risk factors for people without chronic kidney disease do not always apply to people with chronic kidney disease. For example, research has shown that dialysis patients who have higher cholesterol actually have fewer hospitalizations and live longer than those with lower cholesterol. However, this may be true partially because severely malnourished people often have very low cholesterol levels, but are still at increased risk for illness and death.

In addition, there are cardiovascular risk factors unique to chronic kidney disease patients. These include:

• Protein in the urine (proteinuria or albuminuria)
• High phosphorus levels
• High calcium levels
• High levels of parathyroid hormone (PTH)
• Electrolyte imbalances (high or low potassium)
• Fluid overload
• Anemia
• Malnutrition
• Inflammation

High cholesterol for chronic kidney disease patients must be evaluated and treated if cardiovascular disease is present. A low fat or low cholesterol diet may be recommended. In addition, kidney patients benefit from following their kidney diet including keeping potassium, phosphorus, calcium and protein levels in a healthy range.

Cholesterol

There are two sources of cholesterol: that which is made by the liver and that which comes from fat in the foods we eat.  Dietary cholesterol and saturated fats are found in animal products such as meat, poultry, seafood, eggs and dairy  foods. Saturated fats are also found in hydrogenated fats (solid at room temperature). Although we cannot control the amount of cholesterol our bodies produce, we can limit the amount of cholesterol and saturated fat we consume in our diets.

Blood cholesterol is divided into several sub-categories. Cholesterol is carried around the bloodstream on molecules called lipoproteins. There are two main lipoproteins: low-density lipoprotein (LDL) and high-density-lipoprotein (HDL). HDL is considered “good” cholesterol and LDL is “bad” cholesterol.

High levels of “bad” cholesterol and low levels of “good” cholesterol can lead to the development of cardiovascular disease. This is significant because those with chronic kidney disease are at a higher risk of developing CVD or may already have cardiovascular disease. In addition to causing heart disease, cholesterol plaque can also clog the renal arteries and cut off blood flow to the kidneys, resulting in loss of kidney function.

Triglycerides, another fat (lipid) found in the blood, are associated with CVD when levels are too high. People who are at risk for cardiovascular disease can take a blood test called a lipid profile. It is recommended that people with chronic kidney disease have a blood test called a lipid profile each year. 

What are the cholesterol and triglyceride goals for kidney patients?

For good total cholesterol, the goal is less than 200 mg/dL (milligrams per deciliter). Below, Table 1 shows what cholesterol is too low and what is too high.

Table 1.

People with high cholesterol can limit their intake of saturated fat and cholesterol, make other appropriate lifestyle changes and take medicines to put them into a healthier range. For people with low cholesterol, it may be due to malnutrition or inflammation. Your renal dietitian will work with you to make sure you are getting the nutrients you need for good health. If you take medicine to lower cholesterol, acceptable low levels may be drug-related instead of being linked to malnutrition or inflammation. Renal dietitians take this into consideration when assessing their patients’ cholesterol and nutritional status.

Below is Table 2, which shows the LDL (low-density lipoprotein) cholesterol goal for people with different conditions. Remember, LDL is considered bad cholesterol.

Table 2.

Lifestyle changes and cholesterol lowering drugs are prescribed to help lower LDL cholesterol, which can help lower risk of cardiovascular disease.

Table 3 shows good HDL (high-density lipoprotein) cholesterol goals for chronic kidney disease patients.

Table 3.

Table 4 describes triglyceride levels a chronic kidney disease patient should have in order to be at a normal level, compared to what would be considered too high of a count.

Table 4.

Inflammation and malnutrition as a risk factor for CVD in kidney patients

People with chronic kidney disease are especially susceptible to inflammation. Inflammation is where the body’s white blood cells and chemicals protect people from bacteria and viruses. But when chronic kidney disease is involved, inflammation can be a chronic condition triggered by many things. It is suggested that inflammation of the arteries along with high blood pressure damages the artery wall. Inflammation can cause bad (LDL) cholesterol to stick around in the body. Bad cholesterol builds up fatty streaks that eventually thicken and form plaque, narrowing the artery. This plaque can break off and cause a blockage or blood clot. Unfortunately this can lead to a stroke or heart attack, keeping track of your cholesterol levels and eating certain foods may help treat or prevent inflammation.

Patients with chronic kidney disease, especially in the later stages, experience frequent eating problems. Poor appetite results in low calorie and protein intake, a condition known as protein energy malnutrition (PEM). A blood protein called albumin is routinely monitored in kidney patients to check for protein energy malnutrition and inflammation. A healthy result for albumin is 4.0 g/dL or higher. Low albumin is associated with malnutrition and inflammation.

Inflammation related chemicals called cytokines contribute to loss of appetite and malnutrition. If inflammation is chronic or occurs frequently, poor food intake results in lower cholesterol, muscle breakdown and weight loss. The heart becomes weaker due to muscle loss (the heart is a muscle). In addition to worsening malnutrition, inflammation makes cardiovascular problems worse. Low cholesterol in a person who has cardiovascular disease and chronic kidney disease may be very misleading if low cholesterol is due to poor nutrition.

Kidney diets and cholesterol

Compared to a general healthy diet, a kidney diet contains fewer fruits, vegetables and whole grains to limit potassium and phosphorus. Extra fat, sugar and starch may be included to ensure adequate calorie intake. For dialysis patients, eating more animal protein to get enough protein is encouraged. The result is higher cholesterol and fat intake which may increase bad cholesterol and risk of cardiovascular disease. Higher sugar intake may increase triglycerides in some people.

Choosing lean meats, eating fish more often, and selecting low potassium fruits and vegetables high in antioxidants are recommended to help improve a kidney diet and increase protection against cardiovascular disease. Increasing intake of omega-3 fatty acids has a heart protective effect. Good sources of omega-3 fatty acids are cold water oily fish such as salmon, mackerel, tuna, trout and herring, canola oil and flaxseed oil.

Other factors affecting cholesterol levels

Regular aerobic exercise (any exercise, such as walking, jogging or bike riding that raises your heart rate for 20 to 30 minutes at a time) may be the most effective way to increase good cholesterol levels. Exercise also lowers blood pressure and triglycerides. Recent evidence suggests that the duration of exercise, rather than the intensity, is the more important factor in raising good cholesterol.  But any aerobic exercise helps. As chronic kidney disease progresses and uremia develops, chronic kidney disease patients often become inactive because of fatigue, anemia and shortness of breath. Restarting an exercise program after dialysis is started or after transplant will help manage cholesterol and improve your appetite and energy level. Be sure to check with your physician before starting any exercise program.

Obesity results not only in increased bad cholesterol, but also in reduced good cholesterol. If you’re overweight, reducing your weight should increase your good cholesterol levels.

And in case you need another reason to quit smoking, giving up tobacco often results in an increase in good cholesterol levels.

Summary

It is helpful to know your cholesterol levels, especially when you have chronic kidney disease. Replacing saturated fats with monounsaturated fats and eating a healthy diet may go a long way to improving cardiovascular health. Also, maintaining a healthy weight and getting regular aerobic exercise as approved by your physician offers additional health benefits.