Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
Henoch-Schönlein purpura, also known as allergic purpura or anaphylactoid purpura and commonly abbreviated to HSP, is a systemic vasculitis (inflammation of blood vessels) characterized by deposition of immune complexes containing the antibody IgA in the skin and kidney. It occurs mainly in young children.
Typical symptoms include palpable purpura (small hemorrhages in the skin), joint pains and abdominal pain. Most cases are self-limiting and require no treatment apart from symptom control, but the disease may relapse in a third of the cases and cause irreversible kidney damage in about one in a hundred cases.[1] The exact cause of Henoch-Schönlein purpura is unknown, although it may occur after certain viral and bacterial infections, as well as an adverse drug reaction to some medications.
Purpura, arthritis and abdominal pain are known as the classic triad of Henoch-Schönlein purpura.[2] Purpura occur in all cases, joint pains and arthritis in 80%, and abdominal pain in 62%. Some include gastrointestinal hemorrhage as a fourth criterion; this occurs in 33% of cases, sometimes but not necessarily due to intussusception.[3] The purpura typically appear on the legs and buttocks, but may also be seen on the arms, face and trunk. The abdominal pain is colicky in character, and may be accompanied by nausea, vomiting, constipation or diarrhea. There may be blood or mucus in the stools.[4] The joints involved tend to be the ankles, knees, and elbows but arthritis in the hands and feet is possible; the arthritis is non-erosive and hence causes no permanent deformity.[2] Forty percent have evidence of kidney involvement, mainly in the form of hematuria (blood in the urine), but only a quarter will have this in sufficient quantities to be noticeable without laboratory tests.[3] Problems in other organs, such as the central nervous system (brain and spinal cord) and lungs may occur, but much less commonly than the skin, bowel and kidneys.[1]
The disease tends to last about 4 weeks, and then resolves spontaneously.[1]
Of the 40% of patients who develop kidney involvement, almost all have evidence (visible or on urinalysis) of blood in the urine. More than half also have proteinuria (protein in the urine), which in one eighth is severe enough to cause nephrotic syndrome (generalised swelling due to low protein content of the blood). While abnormalities on urinalysis may continue for a long time, only 1% of all HSP patients develop chronic kidney disease.[1] Hypertension (high blood pressure) may occur. Protein loss and high blood pressure, as well as the features on biopsy of the kidney if performed, may predict progression to advanced kidney disease. Adults are more likely than children to develop advanced kidney disease.[1][5]
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%[6]), and raised C-reactive protein (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.[2]
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