Henoch-Schonlein purpura

Definition:
There are many health problems that arise from the fact that the body’s immune system can turn on itself itself and attack its own tissues. These are called autoimmune reactions, and they can happen without warning. Henoch-Schonlein purpura (HSP) is one such reaction.

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In HSP, the immune system is triggered to produce a type of antibody known as IgA which targets and attacks the blood vessels. This causes the blood vessels to become inflamed, a condition called vasculitis.

Although Henoch-Schonlein purpura can affect anyone, it’s most common in children and young adults. Henoch-Schonlein purpura usually improves on its own, but if the kidneys are affected, medical care is generally needed, as well as long-term follow-up to prevent more-serious problems.

Symptoms:
HSP often affects various parts of the body. Most patients are mildly unwell, with a low grade fever. A triad of more specific symptoms usually occurs:

•a characteristic symmetrical skin rash on the lower extremities
•abdominal pain or kidney problems
•arthritis
The characteristic rash of HSP appears as purple spots on the skin, known as purpura which may rapidly merge together to look like bruises. These are usually found over the lower extremities – in particular, the buttocks and lower legs. However, the rash can also appear on the face, trunk and upper extremities – especially the outer side of the arms. It tends to be more prominent in areas where pressure on the skin occurs, from socks or waistbands for example.

When the joints are affected, they may become red, swollen and tender. This is most common in the ankles and knees, but the feet, hands and elbows may also be involved. Fortunately, this is only temporary and permanent deformity doesn’t occur.

Cramping abdominal pain, sometimes with diarrhoea and vomiting, and the passing of blood raises the alarm that the gut has become involved. In up to three percent of cases the bowel may become blocked by a condition called intussusception. Traces of blood or protein found in the urine indicates the kidneys are inflamed (called glomerulonephritis) – this affects up to 50 per cent of older children.

Causes:
In Henoch-Schonlein purpura, some of the body’s small blood vessels become inflamed, which can cause bleeding in the skin, joints, abdomen and kidneys. Why this initial inflammation develops isn’t clear, although it may be the result of an overzealous immune system responding inappropriately to certain triggers.The exact cause for this disorder is unknown.

Some of these triggers may include:

*Viral and bacterial infections, such as strep throat and parvovirus infection — nearly half the children with Henoch-Schonlein purpura develop the disease after an upper respiratory infection

*Certain medicines, including some types of antibiotics and antihistamines

*Insect bites

*Some vaccinations, including those for measles, typhoid, yellow fever and cholera

*Cold weather

*Certain chemicals

* Food allergens.

It’s thought that HSP may be triggered by a viral infection, as up to two-thirds of children will have had a respiratory tract infection (a cough or cold) one to three weeks before HSP appears.

Risk Factors:
*Age. The disease affects primarily children and young adults, with the majority of cases occurring in children between 4 and 6 years of age.

*Sex. Henoch-Schonlein purpura is slightly more common in boys than girls

*Race. White and Asian children are more likely to develop Henoch-Schonlein purpura than black children are.It’s between one and a half and two times more likey to affect boys than girls.

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*Illness. Having an upper respiratory infection or other bacterial or viral illness increases a child’s risk.

*Season. Henoch-Schonlein purpura strikes mainly in autumn, winter and spring, and rarely in summer.Every year in the UK about one person in every 5,000 develops HSP

Complications:-
For most people, symptoms of Henoch-Schonlein purpura improve in a few weeks, leaving no lasting problems. Recurrences are fairly common, however. Children who have severe symptoms appear more likely to have a recurrence, but repeat bouts are usually milder than the initial episode.

Kidney damage
The most serious complication of Henoch-Schonlein purpura is kidney damage, which can cause blood in the urine, swelling and high blood pressure. Most children with kidney problems recover fully, but in a very small percentage of cases, Henoch-Schonlein purpura leads to end-stage kidney disease. In that case, dialysis or a kidney transplant may be needed. Adults are at greater risk than children of developing end-stage kidney disease.

The long-term outcome for people with Henoch-Schonlein purpura appears to depend on whether they develop kidney problems and how severe those problems are.

Bowel obstruction
In rare cases, Henoch-Schonlein purpura can cause a kind of bowel obstruction (intussusception) that reduces blood flow to the intestinal tract and leads to inflammation of other organs, including the pancreas.

Future pregnancies
Women who’ve had Henoch-Schonlein purpura during childhood may be at increased risk of high blood pressure during pregnancy. If you’re pregnant and have a history of Henoch-Schonlein purpura, be sure to tell your doctor about it so that you can be monitored appropriately.

Diagnosis:
The diagnosis is based on the combination of the symptoms, as very few other diseases cause the same symptoms together. Blood tests may show elevated creatinine and urea levels (in kidney involvement), raised IgA levels (in about 50%), and raised CRP or erythrocyte sedimentation rate (ESR) results; none are specific for Henoch–Schönlein purpura. The platelet count may be raised, and distinguishes it from diseases where low platelets are the cause of the purpura, such as idiopathic thrombocytopenic purpura and thrombotic thrombocytopenic purpura.

If there is doubt about the cause of the skin lesions, a biopsy of the skin may be performed to distinguish the purpura from other diseases that cause it, such as vasculitis due to cryoglobulinemia; on microscopy the appearances are of a hypersensitivity vasculitis, and immunofluorescence demonstrates IgA and C3 (a protein of the complement system) in the blood vessel wall.[2] However, overall serum complement levels are normal.

On the basis of symptoms, it is possible to distinguish HSP from hypersensitivity vasculitis (HV). In a series comparing 85 HSP patients with 93 HV patients, five symptoms were found to be indicative of HSP: palpable purpura, abdominal angina, digestive tract hemorrhage (not due to intussussception), hematuria and age less than 20. The presence of three or more of these indicators has an 87% sensitivity for predicting HSP.

Biopsy of the kidney may be performed both to establish the diagnosis or to assess the severity of already suspected kidney disease. The main findings on kidney biopsy are increased cells and Ig deposition in the mesangium (part of the glomerulus, where blood is filtered), white blood cells, and the development of crescents. The changes are indistinguishable from those observed in IgA nephropathy.

Microphotograph of a histological section of human skin prepared for direct immunofluorescence using an anti-IgA antibody, the skin is a biopsy of a patient with Henoch-Schönlein purpura. IgA deposits are found in the walls of small superficial capillaries (yellow arrows). The pale wavy green area on top is the epidermis, the bottom fibrous area is the dermis.HSP can develop after infections with streptococci (?-haemolytic, Lancefield group A), hepatitis B, herpes simplex virus, parvovirus B19, Coxsackievirus, adenovirus, Helicobacter pylori,[5] measles, mumps, rubella, Mycoplasma and numerous others.  Drugs linked to HSP, usually as an idiosyncratic reaction, include the antibiotics vancomycin and cefuroxime, ACE inhibitors enalapril and captopril, anti-inflammatory agent diclofenac, as well as ranitidine and streptokinase. Several diseases have been reported to be associated with HSP, often without a causative link. Only in about 35% of cases can HSP be traced to any of these causes.

The exact cause of HSP is unknown, but most of its features are due to the deposition of abnormal antibodies in the wall of blood vessels, leading to vasculitis. These antibodies are of the subclass IgA1 in polymers; it is uncertain whether the main cause is overproduction (in the digestive tract or the bone marrow) or decreased removal of abnormal IgA from the circulation. It is suspected that abnormalities in the IgA1 molecule may provide an explanation for its abnormal behaviour in both HSP and the related condition IgA nephropathy. One of the characteristics of IgA1 (and IgD) is the presence of an 18 amino acid-long “hinge region” between complement-fixating regions 1 and 2. Of the amino acids, half is proline, while the others are mainly serine and threonine. The majority of the serines and the threonines have elaborate sugar chains, connected through oxygen atoms (O-glycosylation). This process is thought to stabilise the IgA molecule and make it less prone to proteolysis. The first sugar is always N-acetyl-galactosamine (GalNAc), followed by other galactoses and sialic acid. In HSP and IgAN, these sugar chains appear to be deficient. The exact reason for these abnormalities is not known

Treatment:
The condition usually settles down within six weeks, although it can go on for several months. It can recur, sometimes more than once, in as many as one in three people. There is no treatment which has been shown to shorten the duration of the disease or reduce the risk of complications, so no specific treatment is required. However, treatment can be used to relieve the symptoms. Paracetamol or non-steroidal anti-inflammatory medication (such as ibuprofen) may be prescribed to relieve any joint pain. If symptoms persist, corticosteroid therapy may be recommended.

The most serious possible consequence of Henoch-Schonlein purpura is kidney damage. Up to five percent of cases develop progressive kidney disease and ultimately kidney failure (this is more likely in older children and adults). For this reason, regular urine tests to monitor kidney function are important, even once someone has recovered from the acute illness.

Prognosis:
Overall prognosis is good in most patients, with one study showing recovery occurring in 94% and 89% of children and adults, respectively (some having needed treatment).

In children under ten, the condition recurs in about a third of all cases and usually within the first four months after the initial attack.Recurrence is more common in older children and adults.

In general, however, the majority of people who develop HSP make a full recovery without any further problems.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose

Resources:
http://www.mayoclinic.com/health/henoch-schonlein-purpura/DS00838
http://en.wikipedia.org/wiki/Henoch%E2%80%93Sch%C3%B6nlein_purpura
http://www.bbc.co.uk/health/physical_health/conditions/henochschonleinpurpura1.shtml

http://www.nlm.nih.gov/medlineplus/ency/imagepages/19831.htm

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