Dense Deposit Disease

Overview

Dense deposit disease (DDD) is a rare kidney condition. It belongs to a group of diseases called C3 glomerulopathies (say: see-three glom-er-yoo-lop-uh-thees), which damage the tiny filters inside the kidneys. The word 'dense deposit' comes from how the kidney looks under a very powerful microscope — a protein from your immune system leaves thick, dark patches in the kidney filters. These patches make it harder for the kidneys to do their job of cleaning the blood and holding on to protein. DDD is not caused by anything you or your child did, and it is not catching. It is a long-term condition that needs careful monitoring, and most people are looked after by a kidney specialist.

No — DDD is very rare. Best estimates suggest it affects only around 1 to 2 people in every million. Many family doctors may never see a case in their whole career, which is one reason it can take time to be diagnosed.

It most often appears in children between about 5 and 15 years old, and it is one of the more common reasons for a serious kidney problem in childhood. Adults can get it too, sometimes in their 20s or later. It affects boys and girls, men and women. People of any ethnic background can be affected. DDD sometimes runs alongside other conditions, such as an eye change called drusen or a loss of fatty tissue in the upper body, but most people have no other health problems when it starts.

Symptoms

Common symptoms

• Foamy urine — a sign that protein is leaking into the urine
• Urine that looks pink, tea-coloured or brown because of blood
• Puffiness or swelling in the face, around the eyes, in the legs or ankles
• Feeling more tired than usual
• High blood pressure, sometimes found by chance
• Needing to pass urine more often, especially at night
• Getting infections more often than usual
• No symptoms at all — the problem is first spotted on a routine urine test

Symptoms in children

• Puffy eyes or a swollen face first thing in the morning
• Swollen ankles, feet or tummy
• Frothy or bubbly urine
• Poor appetite, slow growth, or seeming to put on weight in the wrong places
• Being unusually tired, clingy or low in energy
• Blood in the urine, which parents may notice as dark or 'Coca-Cola' coloured wee
• Frequent infections or repeated bouts of illness

Symptoms in older adults

• Protein or blood in the urine found on a routine health check
• High blood pressure that is hard to control
• Swelling in the legs that builds up slowly
• Changes in vision, sometimes linked to tiny deposits at the back of the eye
• Tiredness that is put down to age or other long-term conditions
• Gradual loss of kidney function seen on blood tests

Causes

Main causes

• A misfiring complement system. The complement system is a group of proteins in the blood that normally help fight infection and clear away waste. In DDD, it gets stuck in an 'on' position and leaves protein deposits in the kidney filters.
• Sometimes the body makes an antibody (a defensive protein) that keeps the complement system switched on when it should switch off.
• Sometimes there is a change in one of the genes that control the complement system, which can be inherited from a parent.
• Often the trigger is an infection or illness that sets things off, and then the process keeps going even after the infection has gone.

Risk factors

• Having a close relative with a known change in a complement gene (uncommon)
• Having another condition where the immune system attacks the body's own tissues
• Having the fatty tissue change called acquired partial lipodystrophy, where fat is lost from the upper body, face and arms
• Age — it most often starts in childhood or the teenage years
• Nothing at all — in many people there is no clear cause or risk factor, and this is not anyone's fault

When to see a doctor

See a doctor urgently if:

• You or your child has blood in the urine or urine that looks dark, brown or frothy
• Swelling appears around the eyes, face, legs or tummy
• You notice a big jump in weight over a few days without a change in eating
• You or your child feels very tired, is passing much less urine, or looks unwell
• A home blood pressure reading is much higher than usual, or comes with a severe headache or blurred vision

Book a routine appointment if:

• Protein or blood in the urine showed up on a routine test and you want to understand what it means
• Someone in your family has a known complement gene change or a rare kidney disease
• You have high blood pressure that has been hard to control
• You have questions about a diagnosis you have already been given, or about a medicine or diet plan

Diagnosis

There is no single test for DDD. A doctor will start with a conversation about symptoms and a physical check, then look at blood and urine tests. If the results suggest a kidney filter problem, the kidney team will usually recommend a kidney biopsy. A biopsy means taking a tiny sample of kidney tissue with a thin needle, using a scan to guide it. The sample is studied under several kinds of microscope, including a very powerful electron microscope that can actually see the 'dense deposits'. This is what confirms DDD. Blood tests that measure the complement system and genetic tests can help explain why it happened and guide treatment.

Tests that may be done

• Urine tests — to measure protein and check for blood
• Blood tests — to check how well the kidneys are filtering, plus salt and mineral levels
• Blood pressure checks, repeated over time
• Complement tests — looking at levels of specific complement proteins and antibodies that can switch the system on
• A kidney biopsy — a small sample of kidney tissue, looked at under normal light, with special staining, and under an electron microscope
• Genetic testing — to look for changes in complement genes, if your specialist thinks it will help
• An eye examination — to check for the small deposits called drusen at the back of the eye
• Sometimes scans or other tests to rule out other kidney conditions

What to expect at your appointment

A kidney biopsy is usually done as a day case in hospital. You will be asked to lie still for a few hours afterwards and will be given pain relief if needed. Most people go home the same day. Results can take from a few days to a couple of weeks because several different specialist teams need to look at the sample. Waiting for results is often the hardest part, so it can help to write down your questions beforehand and ask who you can call if you are worried while you wait. You may also be offered a referral to a specialist kidney centre, as DDD is rare and best managed by a team that has seen it before.

Treatment

There is no cure for DDD yet, but there is a lot that can be done to protect the kidneys and keep you or your child feeling well. The aims of treatment are to keep blood pressure in a healthy range, reduce the amount of protein leaking into the urine, calm down the overactive complement system where possible, and treat any problems as they come up. Because DDD is rare, treatment is usually planned with a kidney specialist, and you should be involved in every decision.

Self-care at home

• Take your medicines exactly as prescribed, even when you feel well — they are working in the background
• Check your blood pressure at home if your team asks you to, and keep a simple written record
• Cut down on salt — it helps with swelling and blood pressure. Try herbs, spices, lemon and garlic instead of salt
• Keep to any fluid limit your team has set for you
• Weigh yourself at the same time each day if you have swelling, and note any sudden changes
• Stay up to date with vaccines your team recommends, and ask which ones are safe if you take medicines that lower your immune system
• Avoid medicines that can strain the kidneys, such as common painkillers from the anti-inflammatory family — always check with your pharmacist first
• Attend your appointments and urine tests even if you feel fine
• Ask for extra rest when you need it — fatigue is a real part of this condition

Medical treatments

Treatment is tailored to the person. It can include medicines to lower blood pressure and protect the kidneys, medicines that help the body get rid of extra fluid (which reduces swelling), and a low-salt diet to support these. To calm the overactive complement system, some people are offered medicines that tone down the immune system, such as steroids or other immune-calming drugs. A procedure called plasma exchange is sometimes used to remove the proteins that keep the complement system switched on. Newer treatments designed to block specific parts of the complement system are being studied in clinical trials, and your specialist can tell you whether any are suitable for you. People who develop kidney failure are offered dialysis or a kidney transplant. Your kidney team will explain each option and its risks and benefits, and you should feel free to ask why a particular treatment is being suggested.

When is surgery considered?

Surgery is not used to treat DDD itself. There are two procedures that may be needed later on if the kidneys stop working properly. Dialysis is a machine treatment that cleans the blood, and it can be done in hospital or at home. A kidney transplant is an operation to place a healthy kidney from a donor into the body. Transplant is often the best long-term option for people whose kidneys have failed, but DDD can come back in the new kidney in roughly half of people, so the decision is made carefully with your transplant team. Your team will talk you through both options well in advance.

Living with this condition

Life with DDD usually settles into a routine of check-ups, blood and urine tests, and medicines. Many people, especially children, are able to go to school, play, work and take part in normal life, with some adjustments. It helps to keep a simple folder or phone note with your appointments, test results and medicine list, and to bring a list of questions to each visit. Children may need their school to know about their condition, and a school care plan can be arranged. Adults may need to talk to their employer about time off for appointments.

Lifestyle tips

• Stay as active as you comfortably can — gentle, regular movement such as walking, swimming or cycling helps heart and bone health
• Eat a balanced diet and ask to see a kidney dietitian, who can give advice tailored to your blood test results
• Avoid smoking and keep alcohol within safe limits
• Keep a card or phone note listing your condition and medicines, in case you need care elsewhere
• Check with your pharmacist before starting any new medicine, supplement or herbal remedy
• Plan rest into your week — pacing yourself helps with tiredness
• Keep up your vaccines as advised and try to avoid close contact with people who are seriously unwell if your immune system is being treated

Diet and exercise

Diet plays a real part in how well the kidneys are protected. Most people are advised to cut down on salt, because salt raises blood pressure and makes swelling worse. Your team may also talk about the amount of protein you eat, your potassium and phosphate levels, and how much fluid to drink — these targets are personal and depend on your blood tests, so it is worth asking for a referral to a kidney dietitian rather than guessing. In general, fresh home-cooked food, plenty of vegetables and fruit (unless your potassium is high), whole grains and lean protein is a good pattern. Exercise is encouraged and safe for almost everyone with DDD. Start gently, build up, and ask your team if you are unsure about contact sports — especially if you have swelling or have had a biopsy recently.

Mental health and emotional wellbeing

Living with a rare, long-term condition can be hard emotionally. It is completely normal to feel anxious while waiting for test results, angry that this happened, or low and exhausted. Children may worry about being different or missing school, and parents often feel guilty even though nothing could have been done to prevent it. Partners and siblings can feel the strain too. These feelings are not a sign of weakness, and support is available. Talk to your kidney team — many hospitals have psychologists, social workers or counsellors attached to the unit. If you ever have thoughts of harming yourself, please tell someone today and call your local emergency number or a crisis helpline in your country straight away.

Prevention

DDD cannot currently be prevented. It is caused by the way a person's immune system behaves, not by diet, lifestyle choices or anything a parent did. There is no known way to stop it starting. What can be done is to protect the kidneys from further harm — controlling blood pressure, reducing protein in the urine, keeping to treatment and attending check-ups all make a meaningful difference to how the condition unfolds.

Vaccines

If you or your child are treated with medicines that calm the immune system, some vaccines are especially important — but some types of live vaccine are not safe with these treatments. Always check with your kidney team before having any vaccine, and ask which ones they recommend.

Screening programmes

There is no routine population screening for DDD. If a specific complement gene change has been found in someone in your family, your kidney team may suggest testing close relatives and checking their urine and blood pressure. People with DDD need ongoing monitoring, including regular urine protein tests, blood tests and blood pressure checks, even when they feel well — this is how early signs of change get picked up.

Complications

If left untreated

• Gradual loss of kidney function, which over time can lead to kidney failure needing dialysis or a transplant
• High blood pressure, which puts extra strain on the heart and blood vessels
• Heavy protein loss in the urine, which can cause swelling and increase the risk of infections and blood clots
• Changes at the back of the eye (called drusen) that can affect vision over many years
• A change in body shape called acquired partial lipodystrophy, where fat is lost from the upper body, face and arms
• Slower growth in some children, which is why growth is monitored closely
• The condition returning in a transplanted kidney, which happens in roughly half of people who have a transplant

Long-term outlook

DDD affects people differently. Some people stay stable for many years with treatment, while others see their kidney function decline more quickly — on average, around half of people reach kidney failure within about ten years of diagnosis, but that is an average and does not describe any one person. The picture is also improving: blood pressure control, better monitoring and a wave of new treatments being tested in clinical trials are giving real reasons for hope. Many people live full lives with DDD, including after dialysis or a transplant. Your kidney team can give you a clearer idea of what to expect based on your own test results and how things change over time.

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