Allergic purpura (HSP) is a systemic vasculitis that mainly damages the skin, joints, gastrointestinal tract and kidneys. The main clinical manifestation is a characteristic hemorrhagic rash, accompanied by symptoms such as arthralgia, abdominal pain, black stool and kidney damage. Allergic purpura occurs in winter and early spring, and is more common in children, with an incidence of 10-14/100,000. 75% of patients have the disease at the age of 2-11 years, and it is rare after the age of 20 years, but it can develop in adults of all ages. The prevalence of purpura nephritis in allergic purpura is about 34.2-49%, which determines the prognosis of allergic purpura.
The etiology of HSP is not yet clear and may be related to infection and allergic reactions, only a small percentage of children can be identified with the exact allergen. 1/3-2/3 or more patients have upper respiratory tract infection before the onset, but lack of etiological evidence, various infections can trigger HSP, including bacteria, virus, chlamydia and parasites. In addition, cold, medications, food allergies, and mosquito bites can also trigger the onset of the disease.
Allergic purpura is a kind of allergic disease, the cause is divided into two aspects: one is endogenous, including genetic predisposition, allergic constitution and environmental disorders in human body; the second is exogenous, thousands of allergens in nature, including food, mites, pollen, fungi, insects, chemical substances (drugs, formaldehyde, benzene, smoke, etc.), environmental factors, infections, etc.
I. Clinical manifestations of HSP.
1, extra-renal manifestations.
(1), skin manifestations.
The typical rash of HSP is symmetrically distributed, most commonly on the ankles, both lower limbs and buttocks. The rash is the first symptom in about 50% of patients, manifesting as acne-like or lamellar purpura, initially it can be puff-like, after a few hours it turns into a red papule, which does not fade when pressed, some patients can have a boot-like rash, partly with scratching, later it gradually fuses into flakes and turns purple, the rash can fade after about two weeks, the distribution of the rash is gravity-dependent, serious complications can have skin necrosis.
(2), musculoskeletal manifestations.
Arthralgia is the second most common symptom of HSP. The incidence of arthralgia or arthritis is 65-85%, with 17-25% first occurring as joint symptoms, most commonly in the knee and ankle joints, followed by the wrist, elbow, fingers and toes. Joint symptoms are non-ambulatory, often presenting as swollen joints with limited movement, and redness, swelling, heat and pain are rare. Joint symptoms are characterized by transient nature. About 35-70% of patients may have subcutaneous edema, commonly found on the scalp, ears, periocular area and the backs of hands and feet, and of course, periocular edema may also occur in association with renal damage.
(3), gastrointestinal manifestations.
The most common symptom is abdominal pain, manifested as dull pain around the umbilicus, about 75% of children may have direct pressure pain, but no rebound pain, vomiting, black stool (about 50%), a few may have vomiting blood, the incidence of intestinal overlap in 1-5%, for suspected intestinal overlap or intestinal perforation, ultrasound examination is very important.
(4), other: clinical manifestations may include headache, intracranial hemorrhage, heart damage, interstitial lung damage, pulmonary hemorrhage, testicular swelling and pain, etc., which are less common.
2, renal manifestations.
That is, purpura nephritis, clinical manifestations vary in severity and vary greatly. It may occur from simple microscopic hematuria, carnal hematuria, microproteinuria, massive proteinuria to hypertension and renal insufficiency.
Retrospective studies have shown that the incidence and timing of renal damage in children with allergic purpura are as follows: the incidence of proteinuria and/or hematuria in children with HSP is 34.2%, of which 1/5 present with nephrotic syndrome, individual children develop acute renal insufficiency, and the percentage of HSP finally progressing to chronic renal failure is in the range of 1-5%. Renal damage occurs in 85% of cases within 4 weeks, 91% within 6 weeks, and 97% within 6 months. Therefore, even if the starting urine test is normal, it is still necessary to continuously examine for 6 months, and gradually extend the examination interval until the end of one year.
Second, general treatment.
Including avoid wearing tight shoes and socks when skin purpura, avoid sports activities in acute period, avoid allergy-prone food in diet, coarse fiber diet can reduce gastrointestinal symptoms in patients with abdominal pain, avoid exposure to oil fumes, house dust, pollen, formaldehyde, etc. in life, good protection in haze days; pay attention to monitoring of skin, gastrointestinal tract, nervous system, lung, testis and other complications, prophylactic penicillin can be used for patients with frequent attacks Treatment; prevention of infections, such as bacterial infections, viral infections or parasitic infections, especially common respiratory tracts, which are often the causative factor for a large proportion of HSP development.
Based on allergen test results, avoid contact with substances to which you are clearly allergic and avoid eating allergic foods. If very common daily food allergies are detected, under the premise of alternative foods to ensure nutrition, it is recommended to consider adding them one by one after 6 months, consuming small amounts of each food for 1-2 weeks, and if no allergy is present, the ban can be lifted.
Dietary precautions.
1, the rash, abdominal pain attacks during the acute period should be light diet, such as porridge, rotten noodles, soft rice, steamed buns, etc., do not eat greasy food, do not eat raw, cold, hard, fried and other indigestible food.
2, the acute period should be prohibited from eating fish, shrimp and crab, seafood, dairy products, eggs, soy products, onions, garlic, chili, wine and other condiments as far as possible, peanuts, melon seeds, walnuts and other nuts, beverages, jelly and other snacks containing preservatives.
3, should eat more food rich in vitamin C, there are oranges, grapefruit, oranges, apples, pears, strawberries, kiwi, tomatoes and a variety of green leafy vegetables, etc.. Longan, litchi, mango, pineapple, durian and other tropical fruits, children in the north should try not to eat, easy to allergic.
4. Try to reduce the variety of food intake during the acute period to avoid causing repeated allergies. Meat can try to eat pork, its allergic reactions are less, poultry, beef and mutton temporarily do not eat.
5.After 2-4 weeks of remission, according to the allergen test, for the pre-forbidden food that is not allergic, you can add one kind of food every 1-2 weeks, such as beef, chicken, eggs, river fish, milk, etc. Vegetables can also gradually increase the variety.
6.If milk allergy is identified, it will take at least 6 months before a small amount of trial drinking can begin. Most infants can gradually adapt to milk. About 55% of milk-allergic infants can tolerate milk within one year of age, 75% within three years of age, and 90% within six years of age. Small infants with severe milk allergy can be given deeply hydrolyzed formula, or even powdered amino acid formula.