Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that causes the body’s immune system to mistakenly attack its own organs and tissues, causing inflammation and pain, commonly in the skin, joints, kidneys, and brain, and may be fatal. When SLE affects the kidneys, it is called lupus nephritis.
Symptoms for lupus nephritis may include:
- Protein in the urine (proteinuria)
- Urine may be foamy, bubbly, or frothy
- Blood in the urine (hematuria)
- Urine may appear pink or light brown
- Fluid retention (edema)
- Swelling in the legs, ankles, or around the eyes
- High blood pressure (hypertension)
- Weight gain
- Kidney problems
- Joint pain or swelling
- Fever with no known cause
- Muscle pain
- A red rash, often on the face, across the nose and cheeks (called a “butterfly rash” due to its shape)
What Causes Lupus Nephritis?
It is not known what causes lupus nephritis, but factors that may play a role in developing the disease include:
How Is Lupus Nephritis Diagnosed?
Lupus nephritis is diagnosed with a patient history and physical examination, and tests such as:
- Urine test to check for protein and blood
- Blood tests
- Antiphospholipid antibodies
- Protein levels
- Cholesterol
- Glomerular filtration rate (GFR) which shows how well the kidneys filter waste
- Anti-nuclear antibodies (ANA)
- Kidney biopsy
What Is the Treatment for Lupus Nephritis?
Lupus nephritis is treated with medications such as:
- Corticosteroids, such as prednisone
- Immunosuppressive drugs, such as cyclophosphamide (Cytoxan) or mycophenolate mofetil (CellCept)
- Blood pressure medications
- Antimalarials such as hydroxychloroquine (Plaquenil)
- Some chemotherapy drugs
- Diet changes
- Reducing salt (sodium)
- Reducing protein
What Are Complications of Lupus Nephritis?
Complications of lupus nephritis are uncommon because treatment is usually effective. When complications of lupus nephritis occur, they can include:
- Scarring in the kidneys, which occurs with the most severe form of lupus nephritis (diffuse proliferative nephritis)
- Scars are permanent
- Kidney function declines as scars form
- Kidney failure (occurs in 10 to 30 percent of patients)
- Increased risk of cancer, especially B-cell lymphoma, a type of cancer that forms in cells of the immune system
- Increased risk of heart and blood vessel problems
From 
https://www.kidney.org/atoz/content/lupus
https://www.allinforlupusnephritis.com/about-lupus-nephritis/signs-and-symptoms
https://www.niddk.nih.gov/health-information/kidney-disease/lupus-nephritis