Lupus nephritis: symptoms, kidney biopsy and treatment in the UK

Lupus is an autoimmune disease, meaning the immune system attacks the body's own tissues. The UK Kidney Association explains that it can affect the skin, joints, blood vessels and organs such as the heart and kidneys, and that symptoms range from mild to severe and can come and go as flares. When the immune system attacks the kidneys and causes inflammation or damage, this is called lupus nephritis.

Kidney Care UK describes how, in lupus, the body makes antibodies that get deposited around the body in various organs. In the kidney they affect the glomeruli, the filtering units, of which it says there are around a million in the kidneys. If the inflammation is left untreated, Kidney Care UK says it can progress to scarring and kidney failure, but that drug treatments can help avoid this.

Lupus is more common in women, with Kidney Care UK saying nine out of ten cases are in women, most commonly aged 20 to 40, and that prevalence differs between ethnic groups. The UK Kidney Association adds that younger patients and people of Black or Asian ancestry are more likely to develop lupus nephritis. Lupus nephritis is sometimes found when lupus is first diagnosed and sometimes develops later.

Lupus nephritis can cause no symptoms for a long time. When symptoms occur they overlap with other kidney conditions. Kidney Care UK and the UK Kidney Association list the following.

• Frothy urine, which Kidney Care UK says is a sign of protein in the urine.

• Brown urine, a sign of blood in the urine (blood can also be present without being visible).

• Swollen feet, ankles and hands, and puffiness around the eyes and tummy (oedema).

• Fatigue and, according to the UK Kidney Association, loss of appetite.

• High blood pressure.

• Protein and blood in the urine that can only be found on testing.

If you have lupus, the practical message from the UK Kidney Association is to have regular urine tests so any inflammation in the kidneys is found early and treated before more damage is done. Tell your GP, rheumatologist or lupus nurse if you notice swelling around the eyes or ankles, foamy or dark urine, or new high blood pressure readings, rather than waiting for the next scheduled review.

The sources do not list emergency thresholds specific to lupus nephritis. As a general rule, sudden severe breathlessness, chest pain, passing very little or no urine, or confusion with a flare should prompt NHS 111 or, if severe, 999. These are general safety points rather than statements from the cited charities.

Kidney Care UK says lupus nephritis may be picked up in a kidney function test or because of symptoms such as swollen ankles or high blood pressure, and that there may be quite a bit of protein or blood in the urine that is not visible. The amount present is an indication of how inflamed the kidneys are.

Because other inflammatory kidney conditions can cause the same symptoms, it says a kidney biopsy might be done to confirm the diagnosis, and that this can also tell the doctor which class of lupus nephritis you have. The UK Kidney Association says doctors classify it into 6 classes. As it describes them, class 1 is minimal damage often only seen with a special microscope, class 2 some inflammation, class 3 involvement of less than 50% of the kidney's filters, class 4 more than 50%, class 5 thickening of kidney structures with immune deposits, and class 6 more than 90%.

The UK Kidney Association says the aim is to dampen the inflammation and stabilise or improve kidney function. For class 3, 4 or 5 disease it says immunosuppressive drugs are used, and that common ones include steroids, mycophenolate mofetil, rituximab and cyclophosphamide, with hydroxychloroquine an important part of treatment for many people with lupus.

Kidney Care UK adds that hydroxychloroquine is not an immunosuppressant but can help with some lupus symptoms and prevent relapse. It explains that mycophenolate is a tablet that does not affect fertility but is not safe during pregnancy, while cyclophosphamide can affect fertility at high doses. It says that with steroids, probably only 20 to 30 per cent of patients reach full remission by 6 to 12 months and around 60 to 70 per cent reach partial remission within a year, so biologics such as rituximab or belimumab are often added.

Voclosporin was approved by NICE in 2023, and NICE says it is available on the NHS with mycophenolate mofetil for adults with active class 3 to 5 disease. The UK Kidney Association says it is taken as capsules, typically three twice a day, together with mycophenolate.

Other measures matter too. The UK Kidney Association lists keeping blood pressure under control, preventing infections including annual flu, pneumococcal and COVID-19 vaccination, a balanced diet with less salt, and stopping smoking. It says treatment will often need to be continued for years, commonly three years minimum and sometimes lifelong.

The UK Kidney Association says that in most cases treatments are effective and kidney function is preserved, but that for some people the kidneys are damaged and less able to work properly, and that some have a relapse after successful treatment and need further treatment.

If permanent damage cannot be improved with medication, dialysis or a transplant may be considered. The UK Kidney Association says that in general people with lupus do as well on dialysis as those with kidney failure from other causes, and that overall people with lupus do very well after a kidney transplant, with the risk of lupus recurring in the transplant kidney very low (less than 5%). Kidney Care UK quotes a consultant nephrologist saying the outlook is much brighter than in the past.

On the NHS, lupus nephritis care is typically shared between a nephrologist and a rheumatologist, with monitoring through blood tests, urine tests and blood pressure checks and sometimes repeat biopsy, as the UK Kidney Association describes. Access to newer drugs such as voclosporin follows NICE guidance. Private consultations can provide specialist opinions and tests, but the medicines and monitoring needed over years are usually coordinated with an NHS renal or rheumatology team.