Chronic Kidney Disease
Chronic kidney disease is a blanket term that refers to different conditions that cause kidney damage, leading to the loss of kidney function over time. Different types of kidney disease—including inherited conditions, hypertension, diabetes and those caused by chronic inflammation—may lead to kidney damage.
It’s estimated that 15% of American adults have chronic kidney disease, but people are often unaware of it because the condition usually has “silent” symptoms early on—they may not be noticeable until the condition is more advanced, and there has been significant kidney function damage.
People 65 and older are more likely to experience chronic kidney disease, and the condition is slightly more common among men than women.
If chronic kidney disease isn’t discovered or treated until the kidneys have lost significant function, the only treatments may be dialysis, a kidney transplant—or both. But if chronic kidney disease is diagnosed early, treatments, including lifestyle modification and medications, may prevent or slow kidney damage from worsening over time.
“The kidney has many important functions in our body,” says Yale Medicine nephrologist Abraham Aron, MD. “It works as a filter for our blood to get rid of toxins that build up throughout the day, gets rid of extra fluid, regulates our blood pressure, and balances our body’s chemistry and electrolytes.”
It is made up of many small blood vessels that function as an actual filter. Therefore, diseases that damage small blood vessels, like high blood pressure and diabetes, can lead to kidney disease over time. In addition to primary kidney disorders, there are other types of diseases that can affect the kidney, he adds.
“Luckily, recent medical advancements have improved our ability to take care of patients with kidney disease,” says Dr. Aron. “In addition to a healthy lifestyle and managing other medical conditions, there are certain medications available that can slow the progression of kidney disease.
What is chronic kidney disease?
If an individual has chronic kidney disease, it means their kidneys can’t properly filter out blood and toxins. In addition to regulating blood pressure, the kidneys act as a filter for blood that circulates throughout the body. In healthy people, the kidneys remove toxins, waste, and extra fluids that build up in the bloodstream, which the body then removes through urination.
When the kidneys become damaged, they don’t work as efficiently. Over time, the buildup of unwanted materials in the bloodstream may lead to health problems, including high blood pressure and heart disease. The presence of unfiltered toxins and other waste may lead to other health issues as well.
The longer you have kidney disease without seeking treatment for the condition, the more permanent damage your kidneys will experience. Without treatment, kidney disease will progress to end-stage disease, which can only be managed with dialysis or kidney transplantation.
It’s important to note that end-stage kidney disease is not inevitable; when the condition is identified and treated early, it’s often possible to protect existing kidney function with medication and lifestyle habits.
How can chronic kidney disease be caused by high blood pressure and also cause high blood pressure?
The filtering part of the kidney is made up of small blood vessels. High blood pressure can cause damage to small blood vessels and therefore can lead to kidney disease—similar to how pipes under high water pressure over time can become damaged. In addition, because the kidney is involved in controlling our blood pressure, once the kidneys start to get damaged, our blood pressure can rise, which can start a difficult cycle of worsening kidney disease. Because of this, treating high blood pressure, when present, is a cornerstone of treating kidney disease.
What causes chronic kidney disease?
The two most common health conditions associated with chronic kidney disease are diabetes and high blood pressure.
There are other conditions that affect the kidneys’ ability to filter waste out of the blood, too. Some are inherited conditions; others develop due to inflammation, kidney stones, and other factors.
What are the symptoms of chronic kidney disease?
Many people don’t realize that they have chronic kidney disease, because early symptoms are silent. However, the following symptoms of chronic kidney disease may emerge over time:
- Low energy
- Difficulty concentrating
- Difficulty sleeping
- Lowered appetite
- Difficulty exercising at the same intensity as usual
- High blood pressure
- Swollen ankles or feet
- Muscle cramps at night
- Pain in the lower back
- An urge to urinate more often, including at night
- Puffy skin around the eyes
- Dry, itchy skin
What are the risk factors for chronic kidney disease?
People who are at increased risk for chronic kidney disease include those who have:
- High blood pressure
- High cholesterol
- A personal history of smoking
- A family history of chronic kidney disease, kidney failure, or polycystic kidney disease (or other inherited kidney diseases)
- Previous kidney damage
- Diseases that cause kidney inflammation
- Chronic urinary tract infections
- Kidney stones
- Kidney tumors
- Enlarged prostate
How is chronic kidney disease diagnosed?
Doctors can diagnose chronic kidney disease by obtaining a personal and family medical history, along with blood and urine tests, which can confirm kidney dysfunction.
During an office visit, a doctor will ask if you have diabetes, high blood pressure, if you’ve had any kidney problems, or if kidney disease runs in your family. Doctors may ask female patients if they have had recurrent urinary tract infections and male patients if they have had an enlarged prostate. They may also ask if you have frequently taken non-steroidal anti-inflammatory drugs (NSAIDs) or other medications that may impact kidney function.
While people with early chronic kidney disease may not exhibit any symptoms, those with more advanced disease may tell their doctor about symptoms like fatigue, trouble sleeping, and an increased tendency to use the bathroom at night. Doctors may look for signs like swollen ankles in people with these symptoms.
When doctors suspect chronic kidney disease, they will offer the following tests to confirm a diagnosis:
- Blood tests can check levels of creatinine, a waste product produced by muscles. In healthy people, the kidneys remove creatinine from the blood. High levels indicate that the kidneys are not functioning optimally. Typically, when kidney function falls to 50%, creatinine levels in the blood rise significantly. Doctors may also order additional blood work to look for anemia and to check potassium, phosphorus and calcium levels.
- Urine tests look for protein in the urine. High levels are a sign that the kidneys have experienced damage.
An ultrasound to check for kidney stones or other obstructions that may affect kidney function may be needed. In some cases, doctors may want to biopsy the kidney to determine the cause of the problem.
How is chronic kidney disease treated?
The following medications may help to stabilize kidney function, preventing additional loss of function.
- Blood-pressure-lowering medication, such as ACE inhibitors or ARBs, sometimes in combination with calcium channel blockers or other medications, to help to lower blood pressure. People with chronic kidney disease are commonly prescribed diuretics as well, and they are usually asked to follow a low-salt diet.
- Diabetes management is essential for people with diabetes and chronic kidney disease. Managing blood-sugar levels and keeping diabetes well-controlled helps to prevent further kidney damage. People with type 2 diabetes may be prescribed metformin and/or other medications.
- Potassium-lowering medications may be needed if potassium levels are high and dietary changes aren’t effective at lowering levels.
- Iron supplements or prescription medication to help manage anemia may be recommended or prescribed.
Adopting healthy lifestyle habits can also help people with chronic kidney disease preserve their existing kidney function. Positive habits include:
- Eating a low-salt diet
- Avoiding excess fat in the diet
- Eating lower amounts of protein than usual, if directed by a physician
- Eating a low-potassium diet, in some cases
- Losing weight, as needed
- Getting at least 30 minutes of moderate-intensity exercise daily
- Quitting smoking
- Avoiding alcoholic beverages
- Discontinuing use of over-the-counter NSAIDs
When someone has advanced (end-stage) disease, it may be treated with:
- Kidney transplant
What is the outlook for people with chronic kidney disease?
When chronic kidney disease is diagnosed early, people may be able to control the condition with medication and lifestyle habits. Even if the condition is diagnosed later, implementing these changes may help to preserve existing kidney function. Avoiding advanced disease may help people live longer; people with uncontrolled chronic kidney disease are at increased risk of heart attacks, strokes, and other conditions that may be life-shortening.
After someone loses a significant percentage of kidney function, they may reach end-stage kidney disease, which can be treated with dialysis and/or kidney transplant. Many people receive dialysis for years, because there aren’t kidneys available for transplantation. On average, people may be on a transplant waiting list for four or more years before receiving a kidney.
What makes Yale unique in its approach to chronic kidney disease?
“There are many different causes of kidney disease, and some of these causes require unique treatment,” says Dr. Aron. “At Yale, every nephrologist is skilled at treating all types of kidney disease; however, we have a wide range of subspecialists that focus on specific areas of kidney disease such as genetic kidney disease, kidney disease in patients with cancer, kidney disease in pregnant women, and glomerulonephritis, to name a few. In addition, our kidney doctors see patients at many of the surrounding dialysis units and work closely with the transplant center to help facilitate the treatment of those patients who do progress to end-stage kidney disease.”