Lupus nephritis is a kidney disease caused by systemic lupus erythematosus (SLE or lupus). In lupus, the immune system makes antibodies that mistakenly attack the body’s organs and tissues, including the kidneys. These antibodies can harm the kidneys by building up in the tissue and affecting how they work.

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?

Doctors 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, examines the glomeruli, the structures in the kidneys responsible for filtering waste and excess fluid from the blood. Each kidney contains about 1 million glomeruli, which consist of blood vessels and tubules (small tubes) that collect fluid. Damage to these structures, including their mesangial cells, is a hallmark of lupus nephritis and helps determine its stage.

When glomeruli and mesangial cells become damaged, the kidneys cannot 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, including:

• 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 in the legs, hands, and face due to excess fluid in the body
• 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. Proteinuria (protein loss in urine) is a common warning sign that may lead a doctor to do more tests, like a kidney biopsy.

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 will generally have no symptoms.

Class 2: Mesangial Proliferative Glomerulonephritis

Class 2 (class II) involves some kidney damage, unlike class 1. Urine tests may show microscopic amounts of blood or excess protein. A pathologist will be able to detect more changes than class 1.

Class 3: Focal Glomerulonephritis

In class 3 (class III), 50 percent or less of the glomeruli in the kidneys have been affected. A pathologist may find small areas of damage, called lesions in the kidneys. The term “focal” means the damage is limited to certain areas and seen in small pockets. Like class 2, there may be tiny amounts of blood or protein in the urine. 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 50 percent of their glomeruli have been affected. A pathologist may also find larger lesions in the kidney tissue. In this context, “diffuse” means the damage is spread throughout the kidneys. There may be blood and excess 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. Along with the symptoms of the earlier classes, a person may have extreme swelling and active lesions on the kidneys.

Class 6: Advanced Sclerotic

Class 6 (class VI) lupus nephritis occurs when more than 90 percent of the glomeruli in the kidney are damaged. Individuals 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 ESRD, such as nausea, vomiting, fatigue, chest pain, shortness of breath, generalized swelling of the body, cramps, and itching.

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

How Does Disease Stage Influence Treatment?

There are different treatment regimens for the various classes of lupus nephritis. Ultimately, the goal of treatment is to prevent further damage to the kidneys and treat the symptoms of lupus nephritis. Treatment of lupus nephritis varies for each stage, as follows:

• Class 1 — This class does not require a particular treatment. However, the treating rheumatologist will exercise caution and keep the patient on regular follow-up. This class of patients might require treatment if other organ systems of the body are involved, like the blood and lymph nodes, musculoskeletal system, nervous system, and cardiovascular system.
• Class 2 — Some individuals will receive no treatment, but others may be prescribed corticosteroids (steroids) to suppress inflammation and the immune system (immunosuppressive therapy).
• Classes 3 to 5 — In these stages, people will likely receive immunosuppressive drugs, corticosteroids, and drugs to control their blood pressure. The immunosuppressive treatment used for these classes is stronger 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 health care 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.

Find Your Team

MyLupusTeam is the social network for people with lupus and their loved ones. On MyLupusTeam, more than 233,000 members come together to ask questions, give advice, and share their stories with others who understand life with lupus. More than 14,000 members have lupus nephritis.

Are you living with lupus nephritis? Share your experience in the comments below, or start a conversation by posting on your Activities page.