What is membranoproliferative glomerulonephritis (MPGN)?
Membranoproliferative glomerulonephritis (MPGN; also sometimes called mesangiocapillary glomerulonephritis, MCGN) is an immune system disorder thst causes damage to the tiny filters in the kidney.
It occurs when antibodies and/or a part of the immune system called complement are deposited in the kidneys. This affects the kidneys’ ability to filter the blood and can eventually lead to a reduction of kidney function.
The precise diagnosis depends on the location and appearance of the antibody and/or complement deposits within the kidneys.
MPGN affects around 1 in 100,000 people in the UK. Men and women are affected equally.
What are the signs and symptoms of MPGN?
Common symptoms of MPGN include:
- Blood in the urine (haematuria) – the urine may look red or dark brown (like a cola drink). This is more likely to be noticed after an infection such as a cold or sore throat, and usually fades after a few days. The blood may be invisible to the naked eye but seen under a microscope when the urine is tested (microscopic haematuria). It does not cause any pain. The amount of blood in the urine is not an indication of how severe the condition is – more is not necessarily worse.
- Protein in the urine (proteinuria) – this is likely to only be found when tested for by dipping a specially treated paper strip into the urine (urine dipstick,) but if there a lot of protein, the urine may look frothy. The more protein there is in the urine, the more severe the condition is. If a later urine test shows lower levels of protein, this is a sign of improvement.
- Swelling or puffiness (oedema) – this can develop in different parts of the body, especially around the eyes and ankles. Swelling around the eyes tends to be worse first thing in the morning and improve as the day goes on, whereas ankle swelling is usually worse in the evenings. There is no pain associated with the swelling. It is not an allergic reaction but is caused by the kidneys retaining too much water.
- High blood pressure – this can damage the structure of the kidney if it is not treated.
- Mild or moderate anaemia (low iron levels).
Although some people have a spontaneous remission, in most cases the condition remains active.
Half of all people with MPGN will develop kidney failure within 10 years and require dialysis and/or a transplant.
What causes MPGN?
MPGN occurs due to a fault in the body’s immune system that causes antibodies and a substance called complement to be deposited in the kidneys. It is not currently known why this happens.
Antibodies and complement normally work together to target and get rid of infections. When they are deposited in the kidneys, they can build up to damage the tiny filters (glomeruli) that normally filter the blood. This allows excess protein and blood to pass into the urine. Overtime, this leads to a reduction in kidney function and eventual kidney damage.
MPGN can also occur as a complication of chronic infections such as hepatitis.
How is MPGN diagnosed?
MPGN is diagnosed by a kidney biopsy. This can show the precise diagnosis as well as how much damage has already been done to the kidneys.
In MPGN, antibodies and/or complement can be seen in the kidneys’ cells when examined under a microscope after a biopsy.
Blood tests can check complement levels and genetic testing may be offered.
Does MPGN affect other parts of the body?
MPGN can cause hives – itchy, red lumps under the skin that may come and go over several hours or a few days. This is a reaction to the malfunctioning immune system.
Does MPGN run in families?
There is some recent research that MPGN may run in families, but the precise details of any inheritance patterns are still being investigated.
How is MPGN treated?
Treatment focuses on reducing blood pressure with medications known as angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). These medications also help to reduce the loss of protein in the urine, which slows the progress of the condition and prevents or at least delays further kidney damage.
Immunosuppressants such as steroids may also be prescribed to help control the immune system.
Dietary changes may also be recommended, including following a low salt diet to reduce swelling.
A diuretic medication may be prescribed. They work by making the kidneys get rid of excess water and salt, so it does not build up in the body and cause swelling.
Vitamin D supplements may also be recommended if kidney function continues to decline. Any dietary changes should only be undertaken with advice and monitoring by a specialist kidney dietitian.
Dialysis and/or transplant may be needed if kidney damage becomes severe. MPGN can reoccur in the transplanted kidney.
Where can I get more information or support about MPGN?
For more information on MPGN, including its diagnosis, symptoms and treatment, visit the MPGN/DDD Support Group.
Publication date: 11/2023
Review date: 11/2026
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