Inflammation of small blood vessels, the kidneys, and joints, caused by an abnormal immune response
- Most common between the ages of 2 and 8
- Twice as common in boys
- Genetics and lifestyle are not significant factors
In Henoch–Schönlein purpura, small blood vessels are damaged by an abnormal reaction of the immune system, possibly triggered by an infection. Antibodies, which are a component of the immune system and normally fight infection, are deposited in the small blood vessels throughout the body, causing them to become inflamed. The inflammation results in blood leaking out of the vessels into the skin, causing distinctive lesions, mainly on the buttocks and the backs of the legs. Bleeding may also occur from the lining of the intestines. The inflammation may also affect the joints and the kidneys.
Henoch–Schönlein purpura is most common in children between the ages of 2 and 8. The disorder occurs more frequently in the winter months and is more common in boys.
What are the symptoms?
The symptoms usually develop over several days and may include:
Numerous raised, purple lesions that typically appear on the buttocks and legs and sometimes also on the arms and feet.
Periodic attacks of abdominal pain, often with vomiting.
Sometimes, blood in the faeces.
Painful, swollen joints, most often the knees and ankles.
In many children with the condition, the kidneys become inflamed, leading to loss of blood and protein in the urine (see Glomerulonephritis). The blood is usually present in amounts too small to be seen with the naked eye. If the kidneys are badly affected, they may be damaged permanently, which may result in a rise in blood pressure. If the intestines become inflamed, a condition known as intussusception may develop, in which part of the intestine “telescopes” in on itself, causing intestinal obstruction.
How is it diagnosed?
The diagnosis of Henoch–Schönlein purpura is based on the symptoms. Your doctor will probably arrange for a urine test to look for blood or protein, indicating that the kidneys are inflamed. Blood tests will be carried out to assess the function of your child’s kidneys and to rule out other possible causes of the symptoms. In some cases, a small sample of tissue may be removed from the kidney (see Kidney biopsy) or skin (see Skin biopsy) for examination.
What is the treatment?
There is no specific treatment for Henoch–Schönlein purpura. Your doctor will probably advise that your child rests in bed and may prescribe painkillers, such as paracetamol. If the abdominal pain is very severe, he or she may also prescribe corticosteroids. Joint pain usually disappears without permanent damage, and the rash should go away without treatment. Symptoms normally take 2–6 weeks to disappear completely. Kidney function is monitored by checking your child’s blood pressure and by performing blood tests. Urine tests are carried out for months or even years, until no traces of blood or protein remain in the urine. If the kidneys are severely damaged, the doctor may prescribe immunosuppressants. Children with kidney damage require long-term follow-up.
What is the prognosis?
Most children with Henoch–Schönlein purpura make a full recovery with no long-term effects. The symptoms may recur over about a year but are rare thereafter. In rare cases, there is long-term kidney damage that may lead to kidney failure.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.