Once you are diagnosed with coronary heart disease, you have a higher risk factor of developing other complications, including kidney disease. Your doctor will want to keep tabs on a number of different things, including screenings for high blood pressure and cholesterol.
In addition, it is important to keep track of your potassium levels. High potassium levels may indicate a problem with your kidneys. Certain drugs can also cause a high potassium reading. Low potassium levels may be a side-effect of some other drugs prescribed for those with heart disease. Low potassium levels may also occur in other diseases. Your potassium level can be checked with a simple blood test.
It is also important to get screened for chronic kidney disease (CKD). CKD often has no symptoms until your kidneys are severely damaged. Three tests are used to screen for CKD: a urine test, a blood test and a blood pressure check.
What is potassium?
Potassium is a mineral found in all human cells necessary for the body's growth and development. Potassium helps keep water balanced between the cells and the body's fluids. Potassium also helps the nerves respond to stimulation and helps muscles contract.
People with advanced kidney disease may have high levels of potassium in their bodies, which can have serious affects on their health and can even cause death if untreated.
People can also suffer from low potassium. This may be due to taking certain medicines (known as diuretics) which are used to remove extra water from the body. Diuretics are often prescribed for people with heart disease or high blood pressure. Symptoms of low potassium include weakness, constipation and heart rhythm problems.
A simple blood test is needed to check your potassium levels.
What do my potassium test results mean?
According to the National Kidney Foundation,
- Safe zone is a potassium level between 3.5 - 5.0 mEq/L (milliequivalents per liter).
- Caution zone is a potassium level between 5.1 - 6.0 mEq/L. (Be aware that your doctor may recommend your levels be slightly above the lower limit of this zone, if your heart is prone to abnormal rhythms.)
- Danger zone is a potassium level higher than 6 mEq/L.
Some potassium levels require medical treatment and in some cases, urgent attention. While you should follow your doctor's recommendations, certain lifestyle changes are also advised.
If you have high potassium you should limit foods that are high in potassium. Those include bananas, cantaloupe, orange juice, raisins, potatoes, tomatoes, milk, bran, peanut butter and most beans including black, baked and refried.
If you have low potassium, doctors often recommend eating more foods high in potassium. Depending upon the level, the doctor may also suggest a potassium supplement for you. Talk with your doctor about your target potassium levels and suggested approach based on your individual medical needs.
Chronic Kidney Disease (CKD)
Creatinine is a non-toxic chemical that comes from the breakdown of muscle. Creatinine is a waste product that is normally filtered from your blood by your kidneys. In people with CKD, the amount of creatinine in your blood stream rises because your kidneys can't efficiently filter it out. Along with increasing creatinine levels, the amount of protein in your urine may also go up, because the unhealthy kidneys may allow it to leak out.
There are five stages of CKD. Stage 1 has the lowest amount of kidney damage and Stage 5 has the highest amount of damage. People with Stage 5 kidney disease often require dialysis or a kidney transplant.
What are the screenings for kidney disease?
A blood test is used to measure your blood creatinine level. This information can be considered with other factors, such as your age, race and sex to calculate a number describing how well the kidneys are filtering the blood. That number is called an eGFR or estimated glomerular filtration rate (GFR).
For the protein test, you will be asked to provide a small urine sample in your doctor's office. This is sent to the lab for analysis. It is abnormal for the kidneys to allow more than 30 mg of protein to spill into the urine every day.
What are the stages of kidney disease?
There are five stages of kidney disease. Your blood filtration rate, or "GFR", determines what stage of kidney disease you have. People with Stage 1 kidney disease have no decline in their filtration rate but do have other evidence of kidney disease such as protein in their urine.
- Stage 1: GFR = 90+ (Kidney damage with a normal or increased GFR)
- Stage 2: GFR = 60-89 (Kidney damage with mild decrease in GFR)
- Stage 3: GFR = 30-59 (Moderate decrease in GFR)
- Stage 4: GFR = 15-29 (Severe reduction in GFR)
- Stage 5: GFR = Less than 15 (Kidney failure)
People with Stage 5 kidney disease may require dialysis or a kidney transplant to stay alive.
The importance of blood pressure
High blood pressure can cause CKD and is often associated with CKD of any cause. For most people, controlling your blood pressure to 130/80 mmHg is critical to help delay the progression of CKD. Sometimes, your doctor may recommend a higher blood pressure target. Talk with your doctor to find out what the healthiest blood pressure is for you.
Created on 01/03/2012
Updated on 01/04/2012
- National Kidney Foundation. What you need to know about urinalysis.
- United States Department of Health and Human Services: National Kidney & Urologic Diseases Information Clearinghouse (UKUDIC). The kidneys and how they work.
- National Kidney Foundation. Glomerular filtration rate (GFR).
- American Heart Association. Potassium and high blood pressure.