The damage incurred to the kidneys during lupus nephritis is separated into six classes, or stages. Lupus nephritis is caused by the autoimmune disease systemic lupus erythematosus (SLE), which is often just called lupus. In people with lupus, the immune system makes proteins called autoantibodies that attack the body’s organs and tissues, including the kidneys. This is referred to as an autoimmune attack. These autoantibodies cause damage to the kidneys by accumulating in the tissue and by directly attacking the kidneys themselves.
Doctors use the stages of lupus nephritis to describe how much damage has occurred in the kidneys of someone living with the condition. This can help an individual and their doctor make decisions about treatment and track the progression of the disease.
The stages of lupus nephritis are usually diagnosed by looking at kidney tissue under a microscope. This requires a kidney biopsy. A doctor who specializes in analyzing tissue, called a pathologist, will usually assess the amount of damage that has occured to structures in the kidneys called the glomeruli.
There are approximately 1 million glomeruli in each kidney, which consists of a bundle of blood vessels connected to a small tube that collects fluid, called a tubule. The glomeruli filter waste and excess fluid out of the blood and into the urine. The glomeruli contain cells called mesangial cells, which are damaged by lupus nephritis. A pathologist will look at the damage done to the mesangial cells to diagnose the stage of lupus nephritis. When glomeruli and mesangial cells become damaged, the kidneys cannot properly remove waste and excess fluid from the blood. This can lead to the symptoms of lupus nephritis:
A person’s symptoms, along with an analysis of their blood and urine, can help a doctor diagnose which stage of lupus nephritis they may be experiencing.
There are six stages, or classes, of lupus nephritis that progress based on the amount of damage to the kidneys and the kidneys’ function. The following describes the stages of lupus nephritis and the symptoms associated with each stage.
Stage 1 is diagnosed when there is little or no damage done to the kidney, but some immune activity — called an “immune deposit” or “immune complex” — is present. These are complexes of the antibodies made by the immune system. A person with stage 1 lupus nephritis will generally have no symptoms.
Stage 2 is classified as mild renal, or kidney, disease. A pathologist may detect some inflammation in the kidney.
During stage 3, 50 percent or less of the glomeruli in the kidneys have been affected. A pathologist may also detect the presence of lesions in the kidneys. There may also be microscopic amounts of blood or protein in the urine.
Stage 4 is diagnosed when more than 50 percent of the glomeruli have been affected. A pathologist may also find larger lesions in the kidney tissue. The symptoms of stage 4 lupus nephritis include blood or excess protein in the urine and high blood pressure.
During stage 5 lupus nephritis, a pathologist may detect an excessive amount of immune complexes in the kidneys. Symptoms of stage 5 lupus nephritis include high blood pressure, blood or excess protein in the urine, extreme swelling, and active lesions on the kidneys.
Stage 6 lupus nephritis occurs when more than 90 percent of the glomeruli in the kidney are damaged. Individuals with stage 6 lupus nephritis usually develop end-stage renal disease (ESRD). These people are more likely to require dialysis or a kidney transplant. Symptoms of stage 6 lupus nephritis include all of the symptoms associated with lupus nephritis and the added symptoms of ESRD, such as nausea, vomiting, fatigue, chest pain, shortness of breath, cramps, and itching.
There are different treatment regimens for the various stages of lupus nephritis. Ultimately, the goal of treatment is to prevent further damage of the kidneys and treat the symptoms of lupus nephritis, such as high blood pressure. Treatment varies for each stage.
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