Lupus nephritis develops when systemic lupus erythematosus (SLE), or lupus, damages the kidneys. Lupus causes the immune system to attack different parts of the body. If the immune system attacks the kidneys, it can lead to lupus nephritis.

If you or a loved one is living with lupus nephritis — or lupus in general — it’s important to understand who develops the condition, what it looks like, how it can affect you, and how to best manage it. Here are eight facts about lupus nephritis.

1. Lupus Nephritis Is a Kidney Condition

Lupus is an autoimmune disease where the immune system produces autoantibodies. Normal antibodies are important in fighting infections, but in autoimmune diseases, autoantibodies mistakenly attack the body. When autoantibodies in lupus attack the kidneys, this can lead to lupus nephritis, which can vary in severity based on its class.

In lupus, when these autoantibodies attack, they can cause damage over time. They can also directly attack the kidney tissue, leading to inflammation. An inflamed kidney may struggle to do its job, like filtering waste and balancing the fluids in your body.

Classes of Lupus Nephritis

Lupus nephritis can be categorized into six classes, or stages. These classes are determined by the results of a kidney biopsy. A doctor will use the biopsy to look at the amount of kidney damage that has occurred.

Many of the classes of lupus nephritis are measured based on the damage to the glomeruli in the kidneys. Glomeruli are unique structures in the kidney primarily made of tiny, specialized blood vessels that filter out waste from the bloodstream. The classes of lupus nephritis are described as:

• Class 1 — There is little disease involvement in the kidney.
• Class 2 — There is some inflammation in the kidneys.
• Class 3 — Less than half of the glomeruli are affected by nephritis.
• Class 4 — The most severe form, where more than half of the glomeruli are affected by nephritis.
• Class 5 — Deposits of autoantibodies are found around the glomeruli, beneath the glomerular basement membrane, a thin kidney filter that separates blood from urine.
• Class 6 — More than 90 percent of the glomeruli are sclerotic (scarred).

2. About Half of Adults Living With Lupus Develop Lupus Nephritis

It’s fairly common for a person living with lupus to develop lupus nephritis. Around 50 percent of adults with lupus will develop lupus nephritis. Children with lupus are even more likely to have the condition. Around 80 percent of them are likely to develop lupus nephritis.

Most people with lupus nephritis do well over the long term — though they may need to take medications for years and get regular checkups.

Scientists believe that gender and race or ethnicity can play a role in determining who is likely to develop lupus nephritis. Around 90 percent of those living with lupus are women, according to the Lupus Foundation of America. However, men are more likely to have lupus nephritis. Additionally, there are higher rates of lupus nephritis in Black, Hispanic, and Asian American people than in white people.

3. Lupus Nephritis Is Difficult To Prevent — But It’s Treatable

Lupus nephritis can be difficult to prevent in people with lupus. Taking medication that suppresses immune activity or the production of autoantibodies may reduce a person’s likelihood of developing lupus nephritis.

If you develop lupus nephritis, know that most people with the condition do well over the long term — though you may need to take medications for years and get regular checkups.

4. Changes to Urine Are Among Telltale Symptoms of Lupus Nephritis

If you’re living with lupus and notice changes to your urine, lupus nephritis may be the culprit. People with the condition have urinary changes like foamy urine, which is caused by proteinuria (protein in the urine). They also may have hematuria (blood in the urine).

Lupus nephritis symptoms can include changes in your urine, joint swelling, high blood pressure, fever, and a red rash.

Other signs and symptoms of lupus nephritis include:

• Edema (swelling) of the hands, feet, ankles, legs or face
• Hypertension (high blood pressure)
• Fever (in active systemic lupus erythematosus)
• A red rash covering the nose and cheeks (also called a butterfly rash, present in people with lupus)

If you develop any of these symptoms, you should speak with your nephrologist (kidney doctor) as soon as possible. They have several tools to test for lupus nephritis.

5. There Are Tests To Diagnose Lupus Nephritis

The condition is diagnosed using tests that analyze the blood, urine, and kidney tissue. These tests assess the kidney function, as well as any damage.

Urine Test

Damage to the kidneys during nephritis affects the glomeruli. These blood vessels are important for filtering out waste and excess water. These blood vessels filter waste and excess water from the blood while keeping important substances like protein in the bloodstream. The damage to the glomeruli during lupus nephritis leads to extra protein leaking out into the urine. A doctor can order an analysis of the protein levels in someone’s urine to determine if they have lupus nephritis.

Lupus nephritis is diagnosed using tests that analyze the blood, urine, and kidney tissue.

Blood Test

Creatinine is a waste product produced by the natural breakdown of the muscles. When the kidneys are working properly, they will filter creatinine out of the blood and into the urine. Your doctor may order a blood test to look for excess levels of creatinine in the blood to help diagnose lupus nephritis.

Kidney Biopsy

In some cases, a kidney biopsy is needed to diagnose lupus nephritis. This entails removing a very small sample of a person’s kidney tissue. This procedure is usually performed in a hospital or an outpatient center under light sedation or general anesthesia. Once the biopsy is completed, a pathologist — a doctor who specializes in looking at tissue under a microscope — will examine the tissue to look for damage caused by lupus nephritis.

6. There Are Treatments Available for Lupus Nephritis

There’s no cure for lupus nephritis, but treatments can help reduce symptoms and prevent the condition from progressing. People with lupus nephritis can have a positive prognosis (outlook) with treatment.

Treatments for lupus nephritis usually aim to calm the immune system and reduce inflammation. Treatment approaches may also target the symptoms of lupus nephritis, such as swelling in the arms and legs and high blood pressure. Commonly prescribed medicines include immunosuppressive drugs and blood pressure medications.

7. As Many as 30 Percent of People With Lupus Nephritis Develop Kidney Failure

Left untreated, lupus nephritis can lead to severe complications. Among them is long-term kidney damage, or chronic kidney disease (CKD). As CKD progresses and kidney function gets worse, end-stage renal disease (ESRD) — also called kidney failure — may occur. Between 10 percent and 30 percent of people with lupus nephritis will develop ESRD. People with ESRD will need to rely on kidney transplantation or dialysis. Dialysis is a medical procedure that helps remove waste from the blood.

Proliferative nephritis (classes 3 and 4) is the most severe form of lupus nephritis. It causes scars in the tissue of the kidneys. These scars affect kidney function, which worsens as scarring accumulates.

People with lupus nephritis are also at higher risk for heart and blood vessel problems. They may also be at higher risk for some kinds of cancer, including B-cell lymphoma.

8. Dietary Changes Can Help Manage Lupus Nephritis

If you have lupus nephritis, your doctor may recommend changes in your diet. For example, they may suggest adopting a low-sodium diet or limiting how much potassium or phosphorus you consume. They may also suggest limiting your protein — such as meat and dairy products. Everyone with lupus nephritis is different. Before you make changes to your diet, talk to your doctor to see what they recommend.

Talk With Others Who Understand

MyLupusTeam is the social network for people with lupus and their loved ones. On MyLupusTeam, more than 234,000 members come together to ask questions, give advice, and share their stories with others who understand life with lupus. More than 15,000 members have lupus nephritis.

Are you living with lupus nephritis? What’s a surprising fact you learned about the condition? Share your experience in the comments below, or start a conversation by posting on your Activities page.