What is Henoch-Schönlein purpura?
Henoch-Schönlein purpura is a condition that causes three main problems:
- A skin rash with petechiae and purpura. (Petechiae are small, round, red spots. They are caused by bleeding into the skin from tiny blood vessels called capillaries. Purpura are a collection of petechiae. They look a bit like a red bruise on the skin.)
- Abdominal pain.
- Joint pains.
Other parts of the body may also be affected leading to other symptoms and complications (see below). The other most common part of the body that can be affected is the kidneys.
What causes Henoch-Schönlein purpura?
Henoch-Schönlein purpura is an immune-mediated condition. This means that it is a condition that develops because of a reaction of the immune system. It is not clear exactly what causes this reaction but it is thought that something acts as a trigger for Henoch-Schönlein purpura. For example, the trigger may be a particular infection or certain medication, such as certain antibiotics.
The trigger acts as the antigen. The antigen stimulates the immune system to produce an antibody to fight against it and attack it. Immune complexes of the antigen and antibody form. These immune complexes are then deposited in the small blood vessels under the skin, causing inflammation of the blood vessels. (Inflammation of the blood vessels is known as vasculitis.) It is this inflammation that causes the petechiae and purpura. The immune complexes can also be deposited in other tissues of the body – for example, the kidneys, causing inflammation there as well.
The most common infection that has been found to be the trigger for Henoch-Schönlein purpura is an infection with a group of bacteria called Group A streptococcus. This group of bacteria is a common cause of infection of the upper respiratory tract (the throat and the upper airways). So, often, particularly in children, someone who develops Henoch-Schönlein purpura will have had a recent upper respiratory tract infection (within the last few weeks). Other bacterial and viral infections may also be triggers in some people. For example, parvovirus B19, Haemophilus parainfluenzae, Coxsackie virus and adenovirus.
How common is Henoch-Schönlein purpura and who gets it?
Henoch-Schönlein purpura is not that common. In the UK, between 10 and 20 in 100,000 people will develop the condition each year. For some reason, it is up to twice as common in males as in females.
At least 9 in 10 people who get Henoch-Schönlein purpura are children. It is most common in children under the age of 10 but Henoch-Schönlein purpura can also affect older children and adults. Children under the age of two tend to develop milder symptoms. Adults with Henoch-Schönlein purpura tend to develop more severe symptoms and are more likely to develop complications (see below).
What are the symptoms of Henoch-Schönlein purpura?
As mentioned above, often, someone with Henoch-Schönlein purpura will have had an upper respiratory tract infection within the few weeks before they develop the condition. So, for example, they may have had a cough, runny nose, fever and been feeling tired.
Everyone with Henoch-Schönlein purpura will develop a rash of petechiae and purpura. The rash is most commonly found on the legs, buttocks, the elbows and around the waist-line. It is symmetrical which means it affects both sides of the body. It can start off being very red in colour but then usually changes to purple and then a rusty colour over time. The rash is raised (like a bump on the skin) and so the purpura are known as palpable (you can feel them). The rash usually takes about 10 days to fade. A typical purpuric rash on an adult can be seen in the picture.
About 3 in 4 people with Henoch-Schönlein purpura develop inflammation of their joints. Joints, particularly the knees and ankles, can become swollen, tender, warm and painful. The inflammation will gradually clear over time and there is not any lasting damage to the joints. The joint pains tend to come on after the rash has appeared in most people but in some people they can develop before the rash.
Between 6 and 7 in 10 people with Henoch-Schönlein purpura develop pain in their abdomen. The pain can be severe in some people and usually fluctuates in severity, or comes on in waves. Abdominal pain tends to come on about a week after the rash has developed in most cases. Some people may also develop vomiting and diarrhoea.
Are there any complications?
In many people with Henoch-Schönlein purpura, no complications develop. But, complications sometimes develop. They can include the following:
- Kidney involvement – in around half of people with Henoch-Schönlein purpura, the kidneys become affected. If immune complexes are deposited in the kidneys, this can lead to inflammation of the kidneys, known as nephritis. This complication usually develops within one month after the rash starts but can sometimes develop up to six months afterwards. In most people, kidney involvement will get better of its own accord. However, in some people, a more persistent and serious nephritis can develop.
- Bleeding in the gut – about 3 in 10 people with Henoch-Schönlein purpura develop this complication. If immune complexes are deposited in the blood vessels of the wall of the intestine (gut), then this can cause bleeding within the gut (gastrointestinal bleeding). This can lead to symptoms such as passing blood in the stools (faeces). Rarely, bleeding in the gut can be severe and life-threatening.
- Orchitis – about 3 in 10 boys with Henoch-Schönlein purpura develop orchitis. This is inflammation of the testis causing pain, redness and swelling of the scrotum.
- Other complications – there are also some other rare, but serious, complications. For example, inflammation can sometimes affect the brain and nervous system (leading to complications such as seizures), the heart (leading to complications such as a heart attack) and the lungs (leading to complications such as a bleeding into the lungs).
Do I need any investigations?
Henoch-Schönlein purpura is usually suspected because of the typical symptoms. However, a number of investigations may be suggested to help doctors confirm the diagnosis and also to see which parts of the body may be affected by the inflammation. Investigations may include the following:
- Blood tests – for example:
- To look at how the kidneys are working.
- To look for any signs of recent Group A streptococcal infection.
- To confirm that platelet levels are not low. (Platelets are a type of blood cell. In some conditions, a purpuric rash similar to that in Henoch-Schönlein purpura develops because platelet levels have become too low for some reason.)
- To look at immunoglobulin A levels which are usually high in Henoch-Schönlein purpura.
- Skin biopsy – if the diagnosis is uncertain, a biopsy of the skin may be suggested. A very small sample of skin affected by the rash is taken and examined underneath the microscope. There is a typical appearance under the microscope in Henoch-Schönlein purpura.
- Urine dipstick test – a special testing strip can be dipped into a sample of urine to look for signs of any kidney involvement. For example, signs of traces of protein or blood in the urine which may not be seen by the naked eye.
- A blood pressure check – blood pressure can be raised if Henoch-Schönlein purpura involves the kidneys.
- Kidney biopsy – if signs of more severe kidney problems develop (for example, blood tests to look at how the kidneys are working show that they are struggling), a biopsy of the kidneys may be suggested. This can give more information about the kidney inflammation and how severe it may be. A separate leaflet called ‘Biopsy – Kidney’ gives further details.
- Stool test – to look for any signs of blood in the stools (faeces). If there is gastrointestinal bleeding, this can lead to blood in the stools, which sometimes cannot be seen by the naked eye. A special test on the stools can pick up microscopic traces of blood.
- Other tests – if other complications develop, certain other tests may be suggested. For example, if pain in the scrotum develops, an ultrasound scan of the scrotum may be suggested.
What is the treatment for Henoch-Schönlein purpura?
Depending on the symptoms that develop, someone with Henoch-Schönlein purpura may be admitted to hospital for monitoring. In around 9 in 10 people, Henoch-Schönlein purpura will get better of its own accord and so, in most cases, no specific treatment is needed. However, there are a number of things that can help with the symptoms. For example:
- Painkillers – these may help with joint pains. Paracetamol is an example. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen may also be helpful. However, NSAIDs should be avoided in anyone who has suspected kidney complications or any gastrointestinal bleeding. A separate leaflet called ‘Anti-inflammatory Painkillers’ gives further details.
- Rest – resting with the legs raised may help reduce the degree of rash that develops. This is because the petechiae and purpura tend to develop in dependent areas of the body such as the legs.
- Steroid medication – this may be suggested if there are signs that the kidneys are becoming affected. Sometimes steroids are also suggested if other symptoms are severe (such as joint pains or abdominal pain), or if boys develop scrotal pain and swelling.
In addition to this, if something is thought to have triggered Henoch-Schönlein purpura, for example, a specific medication that was being taken, this should be stopped.
Other treatment will depend on whether complications develop. For example, if the kidneys become involved, referral to a kidney specialist for assessment and their advice about treatment may be advised. A kidney biopsy may be suggested to help give the specialist more information and guide them as to the best treatment. Treatment may include steroids and other drugs to help suppress the immune system. Sometimes medication to lower the blood pressure is needed if high blood pressure develops because of kidney involvement.
What is the prognosis (outlook)?
The long-term prognosis (outlook) of Henoch-Schönlein purpura largely depends on whether the kidneys have been involved and, if so, how severe the involvement is.
- If Henoch-Schönlein purpura does not affect the kidneys, most people make a full recovery within about 4 weeks and have no long-lasting problems.
- Kidney involvement is only serious in around 1 in every 10 people.
- In a small number of people (around 2 in every 100), the kidneys can become so severely affected that kidney failure can develop.
Therefore, it is important to monitor for any early signs of kidney problems if someone has Henoch-Schönlein purpura. If kidney problems are detected early, this means that treatment can be started early and this may reduce the chance of any long-term kidney damage. Testing the urine for any signs of kidney damage and measuring the blood pressure may help to detect any signs of kidney involvement.
In about 1 in 3 people, Henoch-Schönlein purpura recurs (come back) within six months. It is more likely to recur if the kidneys have been affected.
As mentioned above, there are other rare, but serious, complications of Henoch-Schönlein purpura which can, in some cases, be life-threatening.
Further help and information
UK National Kidney Federation
The Point, Coach Road, Shireoaks, Worksop, Notts S81 8BW
Helpline: 0845 601 0209 Web: www.kidney.org.uk
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