Caused by systemic lupus erythematosus, lupus nephritis is a serious, and relatively common, kidney disorder.
In September, Selena Gomez shared with her fans via Instagram that she had received a kidney transplant due to complications of lupus. The two kidneys are the primary members of the renal system in the body and are crucial in ensuring that:
- waste and toxic substances are removed;
- hormones controlling blood pressure and volume are regulated; and
- the proper levels of fluids exist throughout the body
Lupus nephritis is a common condition, impacting nearly 40% of people with lupus, according to the Lupus Foundation of America. However, the symptoms of kidney disorders are are often subtle and easy to miss. Because of this, it is important to know the symptoms of lupus nephritis and to speak with your lupus treatment team if you are experiencing any symptoms.
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Lupus nephritis – Advanced definition
Lupus nephritis is a specific type of inflammation in the kidneys known as a glomerulonephritis. In this type of disease, the glomeruli are inflamed.
The glomerulus is a network of tiny tubes that transport blood, known as capillaries. It is found at the beginning of the nephron in the kidney.
Because of some specific blood circulation patterns in this part of the body, there is a lot of hydrostatic pressure in the glomerulus. This pressure is used for ultrafiltration, a process that removes large proteins from the blood cells so that it can be removed from the body in urine.
As part of this process, the glomerus is filled with mesangial cells. These cells make up 30-40% of the cells in the glomerulus. Mesangial cells work to keep this filtering mechanism clean and clear of excess proteins or other residue.
Many tools can be used to diagnose lupus nephritis including blood tests, urinalysis, x-rays, and ultrasounds. Kidney biopsies are also a crucial part of the diagnostic and classification process, even though they are invasive.
Because kidney biopsies are invasive, recent analysis has examined their role. A 2016 article published in Reumatologia explored the question and concluded that: “In daily practice initial and repeat renal biopsies remain an important and valuable tool.” This sentiment was echoed in a 2012 journal article in the Clinical Journal of the American Society of Nephrology.
Lupus nephritis – WHO Classifications
The World Health Organization has subdivided lupus nephritis into 6 stages. The classes represent different severities and require different treatment options. These classes are identified by a clinician examining the kidney biopsy with specialized microscopes and immunofluorescence.
NOTE: Always work with your doctor and/or lupus treatment team to identify the best treatment plan.
Known as: Minimal mesangial glomerulonephritis
Prevalence: Seen in 10-25% of people with lupus (SLE). 5% of lupus nephritis cases are class 1.
Diagnosed: Immune complex (antigen-antibody complex) deposits are specific molecules that can result from SLE. They build up in trace amounts in the glomerulus in class 1 lupus nephritis. This build-up can be seen under an electron microscope. Urinalysis is normal.
Known as: Mesangial proliferative glomerulonephritis
Prevalence: 20% of lupus nephritis cases are class 2
Diagnosed: If there is any masangial hypercellularity (excessive messangial cells in a small defined area) related to immune complex deposits.
Treatment: Typically responds to corticosteroids. Kidney failure is rare.
Known as: Focal glomerulonephritis
Prevalence: 25% of lupus nephritis cases are class 3
Diagnosed: Active lesions exists in less than half of the glomeruli. Usually, lesions occur in one or two focused locations. A person may exhibit microscopic amounts of blood in the urine (hematuria) and/or excess protein in the urine (proteinuria).
Treatment: Typically responds to high doses of corticosteroids. Kidney failure is uncommon.
Known as: Diffuse proliferative nephritis
Prevalence: 40% of lupus nephritis cases are class 4. Very severe subtype.
Diagnosed: More than 50% of the glomeruli are affected with active lesions. Immune complex deposits exist under the endothelial when viewed with an electron microscope. People will experience hematuria and proteinuria. Often, there will be hypertension, elevated serum creatinine, and raises anti-dsDNA titres.
Treatment: Treated with corticosteroids and immunosuppressant drugs. Kidney failure is common in class 4.
Known as: Membranous glomerulonephirits
Prevalence: 10% of lupus nephritis cases are class 5.
Diagnosed: Extreme swelling (edema) and proteinuria. The glomerular capillary wall is thicker in segments, or entirely. May experience renal vein thromboses, a pulmonary embolism, or other thrombotic complications. Active lesions are present.
Treatment: Treated with corticosteroids and immunosuppressant drugs. Kidney failure is uncommon.
Known as: Advanced sclerotic
Diagnosed: Global sclerosis – typically more than 90% of the glomeruli are involved and have active lesions. Class 6 is characterized by progressively worse kidney function.
Kidney disease often presents without obvious symptoms. Because of this, it is important to be on the lookout for the following symptoms:
- foamy urine
- blood in the urine
- dark urine
- changes in the frequency of urination
- water retention or weight gain throughout the body, including the legs and hands
And, always bring up your concerns with your lupus treatment team.