Lupus nephritis is a complication of systemic lupus erythematosus (SLE), the most common type of lupus. Lupus is an autoimmune disease, which means the immune system makes antibodies that mistakenly attack the body’s organs and tissues. When the antibodies attack the kidneys, this causes a kidney disease called lupus nephritis.

Lupus nephritis is separated into six classes or stages. Doctors use the classes of lupus nephritis to describe how much damage has occurred in a person’s kidneys. This can help a person and their doctor make decisions about treatment and track the progression of the disease.

Doctors use the classes of lupus nephritis to describe how much damage has occurred in a person’s kidneys.

How Are the Classes of Lupus Nephritis Diagnosed?

Healthcare providers usually diagnose classes of lupus nephritis by looking at kidney tissue under a microscope. This requires a kidney biopsy — also known as a renal biopsy — which involves removing a small piece of tissue from the kidney.

A pathologist — a doctor who specializes in studying tissue — looks at the glomeruli (blood vessels in the kidneys) that are responsible for filtering waste and excess fluid from the blood. Damage to the glomeruli is a key feature of lupus nephritis and helps determine the stage of the disease.

When glomeruli become damaged, the kidneys can’t properly remove waste and excess fluid from the blood. As a result, important components like protein and blood cells, which should remain in the body, can be lost in the urine. This can lead to symptoms of lupus nephritis such as:

• Proteinuria — Leakage of excess protein into the urine, which causes foamy, frothy urine
• Hematuria — Leakage of blood into the urine, which causes pink or light brown urine
• Edema — Swelling around the eyes or lower body caused by excess fluid
• Hypertension — High blood pressure
• Weight gain from excess fluid
• Frequent urination

Your symptoms, along with an analysis of your blood and urine, can help a doctor diagnose your lupus nephritis stage.

Your symptoms, along with an analysis of your blood and urine, can help a doctor diagnose your lupus nephritis stage.

Classification of Lupus Nephritis

There are six classes of lupus nephritis. The classes are defined by the amount of damage to the kidneys and renal function (how well the kidney works). Classes can be written using Arabic numbers (e.g., class 2 or class 3) or Roman numerals (e.g., class II or class III).

The following describes the six classes of lupus nephritis and the symptoms associated with each stage.

Class 1: Minimal Mesangial Glomerulonephritis

Class 1 (class I) is diagnosed when there’s little or no kidney damage, but some immune activity — called an immune deposit or immune complex — is present. A person with class 1 lupus nephritis usually has normal urine tests or only a small amount of proteinuria.

Class 2: Mesangial Proliferative Glomerulonephritis

Class 2 (class II) involves some kidney damage, unlike class 1. Urine tests may show microscopic (very small) amounts of blood or higher-than-normal protein. When a pathologist examines kidney tissue, they will be able to see more changes than in class 1.

Class 3: Focal Glomerulonephritis

In class 3 (class III), 50 percent or less of the glomeruli in the kidneys have been affected. Pathologists can see immune deposits building up inside the kidney tissue, which is causing damage to the kidneys. There may be more blood or protein in the urine compared to stage 2. A person may also have high blood pressure.

Class 4: Diffuse Proliferative Nephritis

A person is diagnosed with class 4 (class IV) lupus nephritis when more than half of their glomeruli have been affected. A pathologist may see larger amounts of immune deposits building up in the kidney tissue. People in this stage often have blood and high levels of protein in the urine, as well as high blood pressure.

Class 5: Membranous Glomerulonephritis

In class 5 (class V) lupus nephritis, a pathologist may find an excessive amount of immune complexes in the kidneys. People in this stage are also likely to have blood and protein in the urine and high blood pressure.

Class 6: Advanced Sclerotic

Class 6 (class VI) lupus nephritis happens when more than 90 percent of the glomeruli in the kidney are damaged. People with class 6 lupus nephritis usually develop end-stage renal disease (ESRD) — also called kidney failure. These people are more likely to require dialysis or a kidney transplant.

Symptoms of class 6 lupus nephritis include all of the symptoms associated with lupus nephritis and symptoms of kidney failure, including:

• Nausea
• Vomiting
• Fatigue
• Poor appetite
• A metallic taste when eating
• Swelling of the body (especially in the face, ankles, and hands)
• Cramps
• Itching

How Does Disease Stage Influence Treatment?

Treatment regimens for lupus nephritis differ depending on class. The main goal of treatment is to protect the kidneys from further damage and treat the symptoms of lupus nephritis.

Treatment of lupus nephritis varies for each stage. Ultimately, the goal is to treat symptoms and prevent further kidney damage.

Treatment of lupus nephritis varies for each stage, as follows:

• Class 1 — This class doesn’t require a specific treatment. However, the treating rheumatologist will monitor the person closely with regular follow-up visits. Treatment may still be needed if lupus is affecting other organ systems of the body, such as the blood and lymph nodes, musculoskeletal system, nervous system, and cardiovascular system.
• Class 2 — Some people may not need treatment. Others may be prescribed corticosteroids (steroids) to reduce inflammation and calm the immune system (immunosuppressive therapy).
• Classes 3 to 5 — These stages usually require immunosuppressive drugs, corticosteroids, and drugs to control blood pressure. Stronger immunosuppressive treatment is used for these classes because starting treatment at the right time can help prevent permanent kidney damage.
• Class 6 — People with stage 6 lupus nephritis will likely need dialysis or a kidney transplant. At this stage, most of the kidney tissue is damaged, so treatment focuses on supportive care, which means managing symptoms and improving quality of life.

Talk With Your Doctor

Managing lupus nephritis starts with understanding your diagnosis and symptoms. Working with your healthcare team is key to creating a treatment plan that fits your needs and helps protect your kidneys. Getting the right care early on can make a big difference in managing this condition.

Join the Conversation

On MyLupusTeam, people share their experiences with lupus, get advice, and find support from others who understand.

Are you living with lupus nephritis? Let others know in the comments below.