Systemic lupus erythematosus (SLE) is commonly called lupus. It’s a condition in which your immune system begins attacking different areas of your body.
Lupus nephritis is one of the most serious complications of lupus. It occurs when SLE causes your immune system to attack your kidneys. Specifically, the parts of your kidney that filter your blood for waste products.
The kidneys play a vital part in your body’s functioning. They remove waste from your blood. If they’re damaged, you can become very ill. People with damaged kidneys might have to get regular hemodialysis. This is a procedure in which your blood is cleaned by a filtration machine. People with lupus nephritis even need a kidney transplant.
Lupus nephritis symptoms are similar to those of other kidney diseases. They include:
- dark urine
- blood in urine
- foamy, frothy urine
- having to urinate often, especially at night
- puffiness in the feet, ankles, and legs that worsens over the course of the day
- gaining weight
- high blood pressure
One of the first signs of lupus nephritis is blood in your urine or extremely foamy urine. High blood pressure and swelling in your feet also might indicate lupus nephritis. Tests that will help your doctor make a diagnosis include the following:
Your doctor will look for elevated levels of waste products, such as creatinine and urea. Normally, the kidneys filter out these products.
24-Hour Urine Collection
This test measures the kidney’s ability selectively to filter wastes. It determines how much protein appears in urine over 24 hours.
Urine tests measure kidney function. They identify levels of:
- red blood cells
- white blood cells
Iothalamate Clearance Testing
This test uses a contrast dye to see if your kidneys are filtering properly.
Radioactive iothalamate is injected into your blood. Your doctor will then test how quickly it’s excreted in your urine. They may also directly test how quickly it leaves your blood. This is considered to be the most accurate test of kidney filtration speed.
Biopsies are the most accurate and also most invasive way to diagnose kidney disease. Your doctor will insert a long needle through your stomach and into your kidney. They’ll take a sample of kidney tissue to be analyzed for signs of damage.
Ultrasounds use sound waves to create a detailed image of the kidney. Your doctor will look for anything abnormal in the size and shape of your kidney.
After diagnosis, your doctor will want to determine the severity of your kidney damage. The World Health Organization (WHO) developed a system to classify the five different stages of lupus nephritis.
- Stage 1 means there’s no evidence of lupus nephritis.
- Stage 2 is the mildest form, and it’s easily treated with corticosteroids.
- Stage 3 is the earliest stage of advanced lupus. Treatment requires high amounts of corticosteroids. The outlook remains favorable.
- Stage 4 is an advanced stage of lupus. There’s a risk of kidney failure. People with lupus nephritis in this stage require high amounts of corticosteroids and immune suppression medications.
- Stage 5 involves excessive protein loss and swelling. Your doctor will treat this with high amounts of corticosteroids. They may or may not give you drugs that suppress your immune system.
There’s no cure for lupus nephritis. The goal of treatment is to keep the problem from getting worse. Stopping kidney damage early can prevent the need for a kidney transplant.
Treatment can also provide relief from lupus symptoms.
Common treatments include:
- minimizing your intake of protein and salt
- taking blood pressure medication
- using steroids to reduce swelling and inflammation
- taking medicines to suppress your immune system such as prednisone, which reduces immune system damage to the kidneys
Extensive kidney damage may require additional treatment.
The most serious complication associated with lupus nephritis is kidney failure. People with kidney failure will need either dialysis or a kidney transplant.
Dialysis is usually the first choice for treatment, but it will not work indefinitely. Most dialysis patients will eventually need a transplant. However, it may take months or years before a transplant becomes available.
The outlook for people with lupus nephritis varies. Most people see only intermittent symptoms. Their kidney damage may be noticed only during urine tests.
If you have more serious nephritis symptoms, you’re at increased risk for a loss of kidney function. Treatments can be used to slow the course of nephritis, but they aren’t always successful. Talk to your doctor about which treatment is right for you.