Purpura, arthritis and abdominal pain are known as the "classic triad" of HenochSchönlein 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 always, 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 nonerosive 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 is much less common than in the skin, bowel and kidneys.[5]
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.[5] 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.
his disease has some pretty serious complications.