Lupus nephritis is inflammation of the kidney that is caused by systemic lupus erythematosus (SLE). Also called lupus, SLE is an autoimmune disease. With lupus, the body's immune system targets its own body tissues. Lupus nephritis happens when lupus involves the kidneys.
Up to 60% of lupus patients will develop lupus nephritis. When the kidneys are inflamed, they can't function normally and can leak protein. If not controlled, lupus nephritis can lead to kidney failure.
Symptoms of Lupus Nephritis
Lupus nephritis is a serious problem. Its symptoms, though, are not always dramatic. For many, the first noticeable symptom is swelling of the legs, ankles and feet. Less often, there can be swelling in the face or hands.
Other symptoms can vary from person to person and from day to day. They may include:
- Weight gain
- High blood pressure
- Dark urine
- Foamy, frothy urine
- The need to urinate during the night
Not all urinary or kidney problems in people with lupus are due to lupus nephritis. People with lupus may also be prone to urinary tract infections. These cause burning on urination and require treatment with antibiotics. Certain lupus medications can also affect the kidneys and cause swelling and other symptoms similar to those of lupus nephritis. Problems related to these drugs usually go away when the drugs are no longer used.
Lupus Nephritis Diagnosis and Treatment
The diagnosis of lupus nephritis begins with a medical history, physical exam, and evaluation of symptoms. Your doctor will likely order tests to make or confirm a diagnosis. Tests used in diagnosing kidney problems include urine tests, blood tests, imaging tests such as ultrasound, and kidney biopsy.
There are five types of lupus nephritis. Treatment is based on the type of lupus nephritis, which is determined by the biopsy. Since symptoms and severity vary from person to person, treatments are individually tailored to meet a person's particular circumstances.
Medications used in treatment can include:
- Corticosteroids. These strong anti-inflammatory drugs can decrease inflammation. Doctors may prescribe these until the lupus nephritis improves. Because these drugs can cause a variety of potentially serious side effects, they must be monitored carefully. Doctors generally taper down the dosage once the symptoms start to improve.
- Immunosuppressive drugs. These drugs, which are related to the ones used to treat cancer or prevent the rejection of transplanted organs, work by suppressing immune system activity that damages the kidneys. They include azathioprine (Imuran), cyclophosphamide (Cytoxan), voclosporin (Lupkynis) and mycophenolate (Cellcept).
- Medications to prevent blood clots or lower blood pressure if needed
Even with treatment, loss of kidney function sometimes progresses. If both kidneys fail, people with lupus nephritis may need dialysis. Dialysis involves filtering the blood through a machine to remove waste products from the body.
Ultimately, it may be necessary to have a kidney transplant. In those cases, people will need additional drugs to keep their immune system from rejecting the transplanted kidney.
Causes of Lupus Nephritis
The cause of lupus nephritis is the most common form of lupus: systemic lupus erythematosus, or SLE.
Doctors don’t know what exactly causes SLE. But they think something -- or some combinations of things -- triggers your immune system to attack your body. That's why most treatments are aimed at weakening your immune system. The things that lead to this faulty immune response aren’t clear, but scientists think they include:
Genes: There is very little evidence that particular genes directly cause lupus, but there are a number of genes that seem to raise your risk for the disease. For example, people of certain ethnic descent -- Hispanic, Native American, African, Asian, Pacific Island -- are more likely to get lupus, possibly due to shared genes.
Still, it seems clear that genes aren’t enough by themselves to cause the disease. Even in identical twins (which have identical genes) where one twin has lupus, the other twin is only about 30% more likely than normal to develop the disease.
Hormones (maybe): Women get lupus far more often than men. And lupus symptoms seem to increase before monthly periods and during pregnancy when estrogen is higher.
But medications with estrogen, like birth control pills and hormone replacement therapy, don’t seem to raise the risk of lupus. Scientists are trying to figure out what, if any, connection there is between hormones and lupus and why women seem to get the disease more often.
Environment: It can be hard to figure out exactly which things around you can cause lupus. But there are some factors that scientists have strong suspicions about. These include:
- Cigarette smoke
- Silica, a common mineral from the Earth's crust found in sand, stone, concrete, and mortar
- Mercury
- Viruses including Epstein-Barr, herpes zoster (causes shingles), and cytomegalovirus
- UV light
- Stress
Stages of Lupus Nephritis
There are six stages, or “classes,” of lupus nephritis. The higher the stage, the more serious the disease:
Stage 1:
- Minor kidney damage
- No obvious other signs or symptoms
Stage 2:
- Some clear damage to the kidney
- Extra blood or protein in your urine that your health care team can detect with lab tests
Stage 3:
- More damage that amounts to less than 50% of important blood vessels in your kidney
- Higher amounts of blood or protein in urine
- Possible high blood pressure
Stage 4:
- Damage that amounts to more than 50% of important blood vessels in the kidney
- Blood or protein in urine
- Possible high blood pressure
- Possible need for dialysis as kidneys stop working properly
Stage 5:
- Thickening of important parts of the kidney
- Blood or protein in urine
- Possible high blood pressure
- Dialysis or possible kidney transplant
Stage 6:
- Damage to more than 90% of important kidney blood vessels
- When treatment is possible, may need dialysis or kidney transplant
- Plus other signs: Blood or protein in urine and high blood pressure
Lifestyle Changes for Lupus Nephritis
Certain lifestyle habits can help protect the kidneys. People with lupus nephritis should do the following:
- Drink enough fluids to stay well hydrated.
- Eat a low-sodium diet, especially if hypertension is an issue.
- Avoid smoking and drinking alcohol.
- Exercise regularly.
- Maintain a healthy blood pressure.
- Limit cholesterol.
- Avoid medications that can affect the kidneys, such as nonsteroidal anti-inflammatory drugs (NSAIDs).
Your doctor may also recommend that you eat a diet low in potassium, phosphorus, and protein if there is already loss of kidney function.
Although lupus nephritis is a serious problem, most people who receive treatment do not go on to have kidney failure.
Complications of Lupus Nephritis
The most serious complication of lupus nephritis is permanent damage to your kidneys. Your doctor might call this chronic kidney disease, or CKD. In severe cases, your doctor can see scar tissue in your kidneys.
CKD can get worse and worse until your kidneys stop working. This is called kidney failure, though your doctor might call it end-stage renal disease (ESRD). Currently, around 20% of people with lupus nephritis eventually lose kidney function.
Though it’s possible to do everything right and still have serious lupus complications, there are things that raise your risk of complications, such as:
- Late diagnosis: It’s harder to control lupus if symptoms have been allowed to go untreated for some years.
- Poor health care access: You may not be aware of your lupus without regular visits to your doctor. And you can’t treat the disease until you and your doctor know you have it.
- Not taking your medication: You’re more likely to get serious flare-ups that lead to complications if you don’t keep to the treatment steps prescribed by your doctor.
Lupus Nephritis and Race and Ethnicity
For certain ethnic groups, lupus is more likely to lead to complications like lupus nephritis. For example, one study divided people into groups by ethnicity, including groups it labeled whites, Blacks, Asian-Pacific Islanders (APIs), and Hispanics. In that study, Blacks, Hispanics, and APIs had more kidney damage than whites. And all three groups were more likely to develop full-blown lupus nephritis than whites. They also developed more serious symptoms more quickly, often within the first year of diagnosis.
This is really important because later-stage lupus nephritis causes a large percentage of lupus-related serious illness and death.
Scientists aren’t yet sure what accounts for these differences, but they continue to study the subject.