Kidney Disease and Arthritis

Having rheumatoid arthritis increases your risk of potentially serious kidney disease.
| By Marianne Wait

Rheumatoid arthritis (RA) has many health consequences, and evidence suggests that an elevated risk of kidney disease is one of them. Kidney disease also raises your odds of developing heart disease. Since people with RA already have double the average risk for cardiovascular disease, that can spell serious trouble.

How Does RA Affect Kidneys?

According to a 2014 Mayo Clinic study, people with RA have a one in four chance of developing kidney disease compared with a one in five chance for people who don’t have it.  

In an earlier French study of 129 RA patients, known as the MATRIX study (MeThotreXate And Renal Insufficiency), 46% of patients showed some degree of kidney disease.

One type of kidney problem found in people with longstanding RA is amyloidosis. In this condition, “a special type of protein gets deposited that causes kidney failure,” says Eric Matteson, MD, chair of rheumatology at Mayo Clinic in Rochester, Minn.

RA patients may also have other types of kidney disease, although the exact type is not always determined. “Most patients with RA and chronic kidney disease do not undergo a kidney biopsy,” says LaTonya Hickson, MD, a nephrologist at Mayo Clinic. Among patients who did get biopsies, “a variety of renal diseases have been found, including amyloidosis, membranous glomerulonephritis [a buildup of immune substances within the kidney], and other glomerular diseases [those that affect the tiny filters in the kidneys].”

Science Behind the RA–Kidney Link

Experts believe that RA might increase the risk for kidney problems in two main ways. 

Inflammation

“We think it’s the overall inflammatory burden of the disease” that contributes to kidney dysfunction, says Dr. Matteson. “Just like you have increased heart disease risk because of how the inflammation affects your blood vessels, the same is true for the tiny blood vessels in your kidneys.” The more severe your disease, the higher your risk of poor kidney function, he says.

Medications

Most of the medications taken for RA are not directly toxic to the kidneys, says Donald Miller, PharmD, professor of pharmacy practice at North Dakota State University in Fargo. But some can cause problems if you already have reduced kidney function.   

• NSAIDS. Regular doses of over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDS), such as ibuprofen and naproxen, usually don’t pose a problem for relatively healthy people, says Miller. However, all NSAIDs reduce blood flow to the kidneys. This could be dangerous for those with reduced kidney function, which includes many older patients.
• Corticosteroids. Corticosteroids such as prednisone cause fluid retention, which can raise blood pressure. Over time, this can aggravate kidney disease, says Miller.
• Methotrexate. This drug is eliminated through the kidneys. If your kidneys aren’t working as well as they should be, it can build up in your bloodstream, potentially causing an overdose.
• Cyclosporine. A powerful immunosuppressant, cyclosporine may decrease kidney function. About “half of patients develop mild kidney problems while on cyclosporine, and may need to adjust their dosage or discontinue the medication,” according to the American College of Rheumatology. Kidney function usually improves after the drug is stopped.

Symptoms of Kidney Disease

Often, people don’t have symptoms of kidney disease until the disease is advanced. Some of the symptoms, such as fatigue and appetite loss, mimic those of RA. Always tell your doctor about any new or worsening symptoms. Symptoms of advanced kidney disease include:

• Decreased appetite
• Fatigue
• Itchy or darkened skin
• Muscle cramps (especially at night)
• Puffiness around the eyes
• Shortness of breath
• Swollen feet and ankles
• Trouble concentrating
• Trouble sleeping
• Urinating more often

Determining Your Risk for Kidney Disease

There are no formal guidelines for how often RA patients should get tested for kidney disease. However, doctors may begin to test more often now that the risk of kidney disease is better understood, says Dr. Matteson. Simple blood and urine tests can determine how well your kidneys are working.

You are more likely to develop kidney disease if you have:

• Diabetes
• Family history of kidney disease
• Heart disease
• High blood pressure
• High cholesterol

African Americans are about 3.5 times more likely to develop kidney disease than Caucasians, according to the Centers for Disease Control and Prevention.

Safeguard Your Kidneys

If you have rheumatoid arthritis, you can protect your kidneys in several ways.

• Make sure your RA is well controlled. The better inflammation is controlled, the more protected your kidneys should be.
• Talk to your doctor about all your medications. If you have existing kidney problems, your doctor may recommend lower doses of certain medications. NSAIDS are not generally advised for people with existing kidney problems.
• Get tested regularly. “It’s important to know whether your kidney function is close to normal,” says Dr. Miller. The frequency of blood and urine tests will depend on which medications you take and other health conditions you have. Talk to your doctor.
• Control your blood pressure and cholesterol. People with high blood pressure and high cholesterol are more likely to develop kidney disease.
• Drink plenty of fluids. “Hydration is actually really important to good kidney function,” says Dr. Matteson. “A lot of people just don’t drink enough.”
• Watch your salt intake. Eating too much salt may contribute to high blood pressure, which threatens the kidneys.