What is dense deposit disease?
Dense deposit disease (DDD) is an immune system disorder that causes damage to the tiny filters in the kidney (glomeruli). It occurs when part of the immune system called complement C3 is deposited in the kidneys. This affects the kidneys’ ability to filter the blood and can eventually lead to a reduction of kidney function.
DDD is named after the thick layers of complement deposits that are left in the kidneys. It is a subtype of a condition called C3 glomerulopathy (C3G), which itself is a type of membranoproliferative glomerulonephritis (MPGN). These conditions are dealt with separately.
The precise diagnosis depends on the exact location and appearance of the C3 deposits in the kidneys.
DDD affects around 1 in 500,000 people in the UK. Men and women are affected equally. Symptoms usually start between the ages of 5 and 15 but can also occur in adulthood.
DDD was previously known as MPGN type 2 but is now considered a separate condition.
What are the signs and symptoms of DDD?
Common symptoms of DDD 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 be seen only under a microscope 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.
Although some people have a spontaneous remission, in most cases the condition remains active. Half of all people with DDD will develop kidney failure within 10 years and require dialysis and/or a kidney transplant.
What causes DDD?
DDD is an autoimmune condition that occurs due to a fault in the body’s immune system, which causes a substance called complement to be deposited in the kidneys. Complement normally works with antibodies to target and get rid of infections. When it is deposited in the kidneys, it can build up to damage the tiny filters (glomeruli) that normally filter the blood. This makes the filters leak protein and blood into the urine. Overtime, this leads to a reduction in kidney function and eventual kidney damage.
How is DDD diagnosed?
DDD is diagnosed using a kidney biopsy. This can show the precise diagnosis as well as how much damage has already been done to the kidneys.
The complement deposits are seen as long, thick strips when examined under a microscope after a biopsy.
Blood tests can check complement levels and genetic testing may be offered.
Does DDD affect other parts of the body?
Some people with DDD notice a change in their appearance as they gradually lose fat in their face and the upper part of the body over a period of several years (partial lipodystrophy). The skin itself remains normal and the changes may only be noticeable when compared to old photographs.
Complement deposits can also develop in the eye, which may cause long-term vision problems.
Does DDD run in families?
Recent research has found genetic abnormalities in some people with DDD. These abnormalities appear on the genes CFH, CFHR1 and C3, but it is not yet known if or how these variations cause the condition.
Most cases of DDD are not inherited and occur with no family history of the condition.
How is DDD treated?
Treatment is aimed at reducing blood pressure with medications called 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 progression 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 be recommended, including following a low-salt diet to reduce swelling.
A diuretic medication may be prescribed. These work by helping 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 on the advice of and monitoring by a specialist kidney dietitian.
Dialysis and/or transplant may be needed if kidney damage becomes severe. DDD can reoccur in the transplanted kidney, but may be a lot milder and not cause any further symptoms.
Where can I get more information or support about DDD?
For more information on DDD, including its diagnosis, symptoms and treatment, visit the MPGN/DDD Support Group.
Publication date: 11/2023
Review date: 11/2026
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