• Heart and kidneys share medical bond

    January 2008

      PDF icon Heart and kidneys share medical bond (PDF, 700 KB) »

    Two recent studies published in the Archives of Internal Medicine outline a close connection between the heart and the kidneys. Both studies concluded that conditions related to chronic kidney disease (CKD), such as anemia, are also associated with an increased risk of cardiovascular disease. Similarly, the studies also concluded that heart disease is associated with a decline in kidney function and the development of kidney disease.

    “Conditions related to chronic kidney disease, such as anemia, are also associated with an increased risk of cardiovascular disease.” 

    First study

    The first study by Dr. Peter McCullough of William Beaumont Hospital in Michigan and his fellow researchers from around the nation followed 37,153 persons for almost 48 months. All of the participants reported a personal or family history of diabetes, hypertension or kidney disease. The data from the study suggest that kidney disease is associated with cardiovascular disease.

    Using the three markers of kidney disease - anemia, estimated glomerular rate (eGFR, which is the rate at which kidneys filter blood), and microalbuminuria (elevated levels of protein albumin in the urine) - the researchers found more than 25 percent of participants who had all three kidney disease markers also had cardiovascular disease. The researchers suggest screening for cardiovascular disease in patients with all three kidney disease markers even if the patients do not report a history of cardiovascular disease symptoms.

    Second study

    The second study by Dr. Essam Elsayed and his colleagues at Tufts-New England Medical Center and Brigham & Women’s Hospital in Boston examined data from two large cardiovascular health studies comprising 13,826 individuals. The research team found that 7.2 percent of those who had cardiovascular disease at the start of the study experienced a decline in kidney function. This team also concluded that cardiovascular disease is independently associated with a decline in kidney function and the development of kidney disease.

    Until these studies were conducted, interactions between kidney disease and systemic cardiovascular disease (CVD) were poorly documented and explained. In fact, 60 percent of major CVD trials excluded patients with kidney disease. Additionally, 90 percent of those trials did not provide adequate information on kidney function. The recent studies provide novel insights into the close relationship between the kidneys and the heart.

    Understanding kidney function

    The kidneys are located on either side of the spine in the lower middle of the back. The main function of the kidneys is to remove waste products and excess water from the blood. The kidneys also help regulate levels of minerals such as calcium, potassium and sodium in the blood. They also help regulate blood pressure, stimulate red blood cell production and produce an active form of vitamin D needed for bone health. Overall, kidney function can be measured by how quickly blood is filtered through the kidneys. This measure is called a glomerular filtration rate.

  • more-information
  • Five Stages of Kidney Disease

    Stage Description % of Kidney Function
    1 Normal function, but a small amount of blood or protein in urine 90% - 100%
    2 Mild decrease in function; blood or protein in urine 38% - 90%
    3 Moderate decrease in function; blood or protein in urine 30% - 38%
    4 Severe decrease in function; blood or protein in urine 30% - 15%
    5 Kidney failure or end stage renal disease, requiring dialysis or transplant 15% or less

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Page last updated: 8/7/2015 1:59:18 PM
  • What the news means for you

    Basics of chronic kidney disease

    Kevin C. Harned, MD

    Wright, Heather, MDIn general, chronic kidney disease (CKD) develops as we get older. Even though some people will never experience symptoms of CKD, everyone loses kidney function as they age. Starting at age 35, most people lose 1 to 2 percent of kidney function per year. However, in conditions such as poorly controlled high blood pressure, poorly controlled diabetes and morbid obesity, the rate of function loss can increase to 5 to 10 percent per year. At age 80, people typically have 40 to 50 percent of kidney function remaining; a person needs approximately 15 percent of kidney function to survive.

    “If patients with kidney
    disease and CVD follow the recommended regimen, they can not only reduce risk of CVD…, but can also slow the progression of kidney disease in most circumstances.”

    Reducing risk factors

    The publication of these studies has led to a much stronger emphasis on reducing all modifiable risk factors for cerebrovascular/cardiovascular disease (CVD). These studies, published in the Archives of Internal Medicine give hard data that if patients with kidney disease and CVD follow the recommended regimen, they can not only reduce risk of CVD morbidity and mortality, but can also slow the progression of kidney disease in most circumstances.

    The recommended regimen includes:

    1.  Blood pressure should be kept lower than 130/80 if there is no protein in the urine and lower than 125/75 if there is protein in the urine.

    2.  To lower blood pressure and to help reduce the amount of protein a person spills into his or her urine (as a result of kidney disease), patients should use medications such as angiotensin converting enzyme inhibitors (ACEIs) and/or angiotensin 2 receptor blockers (ARBs). Although rare, adverse effects are possible with these medications, so patients should discuss the risks with their doctor before taking them.

    3.  Diabetics must have strict blood sugar control measured by hemoglobin A1c (glycohemoglobin), with a target level of at least 7 percent but preferably below 6.5 percent. 

    4.  Patients must also strictly control cholesterol and keep low-density lipoprotein (LDL) under 100 and high-density lipoproteins (HDL) over 40.

    5.  It is necessary to stop smoking completely. We feel even second-hand smoke is bad, although there are no trials that have examined this specific factor.

    6.  Patients need to also alter their diets to lessen the amount of phosphorus consumed. A dietitian or nutritionist can help determine the best diet for each patient. Without the kidneys to rid the blood of phosphorus, levels of phosphorus rise and can lead to hardening of the arteries, resulting in an increased risk of heart attacks, strokes and kidney disease.

    7.  Patients should take platelet aggregation inhibitors such as daily baby aspirin or in some circumstances more potent medications such as Plavix.

    Treatments and stages of CKD

    Treatment for CKD varies depending on how advanced the disease is at the time of diagnosis. There are five stages of kidney disease (see table below).

    At stage 3 the body has trouble with calcium and phosphorous. This is what ultimately increases the risk of cardiovascular death. As the body loses kidney function, it cannot get rid of phosphorus. In an attempt to correct the excess phosphorus, the body’s hormones (from the parathyroid glands in the neck) will react to try to force the kidneys into excreting the necessary phosphorus back to a normal level. However, the downside of that is the same hormone reacts with the bones to "leech" minerals from them.

    The end result is that minerals are being removed from the bone and cannot be excreted from the kidneys. Consequently they become deposited in tissues, mainly the blood vessels, resulting in hardening of the arteries, which can lead to a heart attack or stroke.

    Symptoms and tests for kidney disease

    Everyone at some point should have a screening for kidney disease. I recommend most people get screened by age 30.

    However, if you are a diabetic, have hypertension or coronary artery disease and have not been checked, you should be screened regardless of age. Typically, those with type 1 diabetes should be screened five years after diagnosis while those with type 2 diabetes should be screened immediately upon diagnosis. Additionally, those who take NSAID drugs (such as ibuprofen, Advil, Motrin, Aleve or naproxen) frequently should also get screened as those drugs can increase your chances of developing kidney disease.

    Lifestyle changes

    Kidney disease does worsen over time, but lifestyle changes can slow down the progression. The absolute most effective way to slow the progression of kidney disease is by keeping your blood pressure below 130/80 or below 125/75 if you have kidney disease and protein in the urine. Weight control is also very important. Stay within an ideal body weight and do at least 30 minutes of cardiovascular exercise three times a week. Control your diet and eat foods low in phosphorus to decrease the workload of the kidneys. Avoid frequent and high doses of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, Motrin, Advil and Aleve/naproxen over a long period of time.

    Dr. Harned is a UK HealthCare nephrologist and an associate professor of internal medicine at UK College of Medicine.

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