What is it?
Systemic lupus erythematosus (SLE) – lupus – is a long-term condition which can cause inflammation to the skin, joints and organs (including the kidneys). It’s an autoimmune disease, meaning that the body's natural defence system (immune system) turns on itself and starts to attack healthy tissues.
Lupus affects women more than men and is more common in black, Asian and Hispanic people. It can range from mild to severe and symptoms can suddenly flare up after long periods of stability. Occasionally flare ups can be life-threatening.
What are the causes
Around six in ten people with lupus will develop kidney disease. It can be caused by antibodies, sent out to attack problems elsewhere in the body, getting stuck in the glomeruli (the tiny filters in the kidney), and then attacking them by mistake. This type of disease, characterised by damage to the glomeruli, is generally known as glomerulonephritis.
It is not clear why the immune system goes wrong. There may be some trigger, such as an infection or an adverse reaction to a drug. Certain factors can also worsen lupus, including infections, hormonal changes related to oestrogen such as periods, the combined oral contraceptive pill, pregnancy, and the menopause, having an operation, exposure to sunlight and possibly stress.
Common lupus symptoms include tiredness and fatigue, joint pains and skin rashes.
The commonest symptom of kidney disease in lupus is water retention, causing swelling of the face, limbs and abdomen. This is caused by leakages of protein in the urine (proteinuria) due to damaged glomeruli. If the protein leak is severe it may cause nephrotic syndrome.
If kidney damage is well advanced, other symptoms including itching and muscle cramps, may also occur.
Blood tests which highlight abnormal antibodies and activation of particular aspects of your immune system (e.g. the complement system) can indicate that you have lupus. X-rays and scans may also be used to check your organs.
Blood and urine tests will also be used to gauge your kidney function and look for the presence of protein in your urine.
If significant kidney damage is suspected a kidney biopsy may be required. This is a medical procedure to take small samples of the kidney away to look at under a microscope and can help pinpoint the kidney diseases that are causing the damage.
If biopsy findings and blood and urine tests indicate significant kidney disease this will require treatment to prevent long-term damage to the kidneys. Lupus and kidney disease caused by lupus can be treated by a combination of drugs, most of which suppress your overactive immune system. These aim to induce a remission (make the disease ‘quiet’) and then maintain this to prevent flares, so treatment is needed for many years – usually a minimum of three.
The treatments include medicines such as:
- hydroxychloroquine (not an immunosuppressant but very good at treating certain symptoms of lupus, preventing flares and protecting babies in the womb)
- steroids (ideally only for a short time due to side effects)
- mycophenolate mofetil (also known as MMF), or cyclophosphamide or azathioprine
Some medicines are given by injections and may include specialised drugs known as monoclonal antibodies, the commonest used being rituximab.
Other treatments may include:
- medicines such as ACE Inhibitors and ARBs to control blood pressure and protein loss
- diuretics (water tablets) to reduce water retention
- antibiotics to treat any infections
- Vitamin D to protect your bones, especially if you are taking steroids
In some cases, treatment is unable to prevent further kidney damage and kidney failure may occur – which can also be described as end-stage kidney disease (ESKD). This can lead to the need for kidney dialysis or a kidney transplant.
Lupus most commonly affects women of child bearing age. Lupus itself can sometimes cause complications in pregnancy and several of the immunosuppressants must not be used when trying to get pregnant or when pregnant. It is also very important that your lupus is in remission (‘quiet’) in the months before getting pregnant.
Please ensure you discuss your pregnancy plans with your doctor before you become pregnant. They can explain potential risks, help you decide on the best timing and change any medications in advance to ensure you are on baby-safe medications when pregnant. They may also refer you to a specialist for pre-pregnancy planning.
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Why we need more research
Whilst the treatments we have for lupus kidney disease are good, they have many drawbacks and different treatments work for different patients. More is being understood about the mechanisms that lead to kidney involvement in lupus and there are several new and very promising medications being developed.
To work out the best combination of treatments we have to do randomised controlled trials (where participants are randomly allocated to either the group receiving the treatment under investigation or to a group receiving standard treatment). These test whether new treatments or different combinations of established treatments, do truly offer benefit to patients.
Trials are rigorously controlled to ensure people are safe. They can involve more visits and tests than routine treatment. Doctors looking after patients in trials have to have special training to understand what is expected of them and patient safety is at the absolute heart of any study.
Sometimes the research being undertaken is to understand mechanisms or changes that occur in more detail and are not part of a treatment trial - you may simply be asked questions, or have some extra blood and/or urine samples taken.
Your participation in research is exceptionally valuable for improving the future of people with lupus kidney disease. You can ask your doctor about any research that you might be able to participate in and consider joining our Kidney Voices for Research network.
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