Lupus nephritis is a complication of systemic lupus erythematosus (SLE). It occurs when the immune system mistakenly attacks the kidneys, resulting in inflammation and organ damage.
SLE is the most common form of lupus. It is a systemic condition, meaning it can affect multiple organs, including the kidneys, and causes widespread inflammation throughout the body. Without treatment, lupus nephritis can lead to permanent kidney damage and kidney failure.
In this article, we will discuss lupus nephritis, including its symptoms, stages, treatment, and more.
Because lupus nephritis causes scarring and swelling of the glomeruli, it affects the kidneys’ ability to perform their functions,
- filtering waste from the blood
- maintaining the fluid and electrolyte balance
- regulating hormone levels for crucial bodily processes
- Blood in the urine: Also known as hematuria, this symptom occurs as damage to the glomeruli allows blood to leak into the urine, which may make it look pink or light brown.
- Protein in the urine: Also known as proteinuria, damage to the glomeruli can also result in protein leaking into urine. This may give urine a foamy appearance.
- High blood pressure: Also known as hypertension, damage to the glomeruli results in the kidneys being unable to remove waste and extra fluid. Having extra fluid in the blood vessels can increase blood pressure.
- Edema: Because the kidneys are unable to filter and remove excess fluids, people may experience swelling in body parts such as the legs, ankles, or around the eyes.
- Weight gain: People may also notice weight gain from the extra fluid.
Each kidney contains more than 1 million functional units known as nephrons. Each nephron contains a small network of blood vessels known as the glomerulus. Health experts may refer to the glomerulus as the “filtering unit” of the kidney.
Lupus nephritis is one of the
The rate of lupus nephritis can vary depending on the population. Evidence suggests it can vary from 15–45%.
Certain racial and ethnic groups may experience a higher chance of lupus nephritis. Genetic components may also predispose some people with SLE to develop lupus nephritis. For example, a variation in the APOL1 gene seen in African American populations is associated with lupus nephritis.
- being male (however, the likelihood of lupus is higher in females)
- younger age (childhood or between the ages of 20–40)
- having African, Hispanic, or Asian ethnicity
Aside from getting a person’s thorough medical history and doing a physical examination, doctors use a range of tests to check a person’s kidney function and diagnose lupus nephritis.
These diagnostic tests can
- Urine tests: A urine test typically involves a dipstick test, where a chemically treated strip of paper changes color in the presence of blood or protein. Having blood or protein in urine indicates kidney damage. A laboratory technician may also examine the urine sample under a microscope to look for kidney cells.
- Blood tests: Some blood tests can help measure kidney function. For example, a doctor may measure creatinine levels. Creatine is a waste product the kidneys remove from the blood. Higher levels of creatinine suggest the kidneys are not functioning properly.
- Kidney biopsy: This type of biopsy involves a doctor taking a small sample of kidney tissue for examination under a microscope. A doctor performs the biopsy using imaging techniques to help guide the biopsy needle into the kidney. A pathologist then examines the tissue and can confirm the diagnosis, determine disease progression, and help guide treatment.
Based on the kidney biopsy, a doctor will know the stage or classification of lupus nephritis. The six stages, or classes, are based on:
- cell changes in the glomeruli as seen under the microscope
- immune deposits seen on immunofluorescence
- electronic microscopy
Class 1, or minimal mesangial lupus nephritis
This classification typically involves minimal damage to the kidneys. It has no obvious signs or symptoms.
Class 2, or proliferative mesangial lupus nephritis
Class 2 will show some damage to the kidneys. It will also present with small amounts of blood, protein, or both in the urine.
Class 3, or focal lupus nephritis
This classification will involve damage to less than 50% of the glomeruli in the kidneys. A person’s urine will contain higher amounts of blood, protein, or both. They may also have high blood pressure.
Class 4, or diffuse lupus nephritis
Class 4 involves damage to more than half of the glomerulus. A person will have high blood pressure. They may require dialysis as kidney function begins to worsen.
Class 5, or membranous lupus nephritis
This classification involves thickening and scarring of the important structures within the kidney. A person will have high levels of blood, protein, or both in their urine as well as high blood pressure. They may also require dialysis or a kidney transplant.
Class 6, or advanced sclerosing lupus nephritis
This is the final classification. It involves damage to more than 90% of the important blood vessels in the kidney. A person will likely require dialysis or a kidney transplant.
Currently, there is no cure for lupus nephritis. The goal of
- reduce kidney inflammation
- reduce immune system activity
- prevent the immune system from attacking the kidneys
Doctors base the treatment on the class of lupus nephritis the person has. Class 1 and 2 may not require specific treatment, but further classes do.
Treatment may involve:
A doctor will usually prescribe different medications to help suppress the immune system and lower blood pressure. This can include medications such as:
- mycophenolate mofetil
- ACE inhibitors
- calcium channel blockers
A doctor will likely advise a person to make dietary changes and encourage eating foods that support kidney health and can help lower blood pressure. This typically involves foods with less salt, sodium, phosphorus, and potassium. For example, this may include foods such as:
- lean meat
- skinless poultry
Potential complications of lupus nephritis may include:
Lupus nephritis refers to a potential, common complication of lupus. It describes when the immune system mistakenly attacks the kidneys, resulting in inflammation and damage, which affects their function.
Currently, there is no cure for lupus nephritis. Treatment focuses on reducing inflammation and immune system activity to prevent further damage to the kidneys.