Expert discusses impact of lupus on kidneys
May is Lupus Awareness Month, and while most people have heard of the disease and its impact on the body, a lesser known fact is that lupus, an autoimmune disease, is linked to kidney damage. Baylor College of Medicine’s Dr. Rajeev Raghavan explains the impact that lupus can have on your kidneys.
“We don’t know what causes lupus, but it is believed to be secondary to a number of different factors, such as genetic, environmental or hormonal factors. The result is that lupus affects multiple organ systems, including the kidneys,” said Raghavan, associate professor of medicine in the section of nephrology.
Raghavan explained that the kidneys have the complex task to clean the blood, filter waste and at the same time, remove excess fluids. The kidneys also play a big role in the hormonal functions of the body, for example they regulate vitamin D levels and stimulate red blood cell synthesis.
“Since lupus is an autoimmune disease, the result is antibody formation, which attack organs, including the kidneys, and result in inflammation,” Raghavan said. “Around 40 percent of patients with lupus have kidney disease, and this is detectable by examining the urine for blood or protein.”
Once the initial signs of kidney disease appear, the final diagnosis requires a kidney biopsy, Raghavan said. He explained that the biopsy is a fairly simple outpatient procedure and after it’s done, doctors are able to look at the tissue under a microscope to determine how severe the lupus is or what type of lupus it is. From there, doctors come up with personalized therapy for the patient with lupus involving the kidneys, which is known as lupus nephritis.
“When you have lupus nephritis the treatment is quite effective – only about 5 to 10 percent of those patients will progress on to really advanced kidney failure where they need dialysis or a kidney transplant,” Raghavan said.
There are two types of treatment options, he said. The first is non-selective, which means that it’s the same treatment given to any patient who has protein or blood in their urine whether it is due to lupus or diabetes or another disease. This treatment involves taking steps such as restricting sodium intake to about 2.3 grams per day and controlling blood pressure, which should stay around 130 over 80. The addition of medications such as angiotensin converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) may be necessary.
In addition, patients with lupus may also be treated with medications that affect the immune system, Raghavan said. Although these drugs have a few more side effects related to repressing the immune system, these are well-tolerated and commonly used drugs to treat patients with severe lupus nephritis.
Raghavan said there is no way to prevent kidney disease due to lupus.
“All we know is that if you have kidney disease because of lupus, we have medications to control and treat the disease. Early diagnosis and treatment results in a high success rate in the sense that very few treated patients will require dialysis or transplantation.”