allergic purpura

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Allergic Purpura



Allergic purpura (AP) is an allergic reaction of unknown origin causing red patches on the skin and other symptoms. AP is also called Henoch-Schonlein purpura, named after the two doctors who first described it.


"Purpura" is a bleeding disorder that occurs when capillaries rupture, allowing small amounts of blood to accumulate in the surrounding tissues. In AP, this occurs because the capillaries are blocked by protein complexes formed during an abnormal immune reaction. The skin is the most obvious site of reaction, but the joints, gastrointestinal tract, and kidneys are also often affected.
AP affects approximately 35,000 people in the United States each year. Most cases are children between the ages of two and seven. Boys are affected more often than girls, and most cases occur from late fall to winter.

Causes and symptoms


AP is caused by a reaction involving antibodies, special proteins of the immune system. Antibodies are designed to bind with foreign proteins, called antigens. In some situations, antigen-antibody complexes can become too large to remain suspended in the bloodstream. When this occurs, they precipitate out and become lodged in the capillaries. This can cause the capillary to burst, allowing a local hemorrhage.
The source of the antigen causing AP is unknown. Antigens may be introduced by bacterial or viral infection. More than 75% of patients report having had an infection of the throat, upper respiratory tract, or gastrointestinal system several weeks before the onset of AP. Other complex molecules can act as antigens as well, including drugs such as antibiotics or vaccines. Otherwise harmless substances that stimulate an immune reaction are known as allergens. Drug allergens that may cause AP include penicillin, ampicillin, erythromycin, and quinine. Vaccines possibly linked to AP include those for typhoid, measles, cholera, and yellow fever.


The onset of AP may be preceded by a headache, fever, and loss of appetite. Most patients first develop an itchy skin rash. The rash is red, either flat or raised, and may be small and freckle-like. The rash may also be larger, resembling a bruise. Rashes become purple and then rust colored over the course of a day, and fade after several weeks. Rashes are most common on the buttocks, abdomen, and lower extremities. Rashes higher on the body may also occur, especially in younger children.
Joint pain and swelling is common, especially in the knees and ankles. Abdominal pain occurs in almost all patients, along with blood in the body waste (feces). About half of all patients show blood in the urine, low urine volume, or other signs of kidney involvement. Kidney failure may occur due to widespread obstruction of the capillaries in the filtering structures called glomeruli. Kidney failure develops in about 5% of all patients, and in 15% of those with elevated blood or protein in the urine.
Less common symptoms include prolonged headache, fever, and pain and swelling of the scrotum. Involvement of other organ systems may lead to heart attack (myocardial infarction), inflammation of the pancreas (pancreatitis), intestinal obstruction, or bowel perforation.


Diagnosis of AP is based on the symptoms and their development, a careful medical history, and blood and urine tests. X rays or computed tomography scans (CT) may be performed to assess complications in the bowel or other internal organs.


Most cases of AP resolve completely without treatment. Nonetheless, a hospital stay is required because of the possibility of serious complications. Non-aspirin pain relievers may be given for joint pain. Corticosteroids (like prednisone) are sometimes used, although not all specialists agree on their utility. Kidney involvement requires monitoring and correction of blood fluids and electrolytes.

Key terms

Glomeruli — Knots of capillaries in the kidneys responsible for filtering the blood (singular, glomerulus).
Patients with severe kidney complications may require a kidney biopsy so that tissue can be analyzed. Even after all other symptoms subside, elevated levels of blood or protein in the urine may persist for months and require regular monitoring. Hypertension or kidney failure may develop months or even years after the acute phase of the disease. Kidney failure requires dialysis or transplantation.


Most people who develop AP become better on their own after several weeks. About half of all patients have at least one recurrence. Cases that do not have kidney complications usually have the best prognosis.



Andreoli, S. P. "Chronic Glomerulonephritis in Childhood. Membranoproliferative Glomerulonephritis, Henoch-Schonlein PurpuraNnephritis, and IgA Nephropathy." Pediatric Clinics of North America 42, no. 6 (December 1995): 1487-1503.


"Henoch-Schonlein Purpura." Vanderbilt University Medical Center. 〈〉.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


a hemorrhagic disease characterized by extravasation of blood into the tissues, under the skin, and through the mucous membranes, and producing spontaneous bruises, ecchymoses, and petechiae (small hemorrhagic spots) on the skin. (See plate in Dermatology Atlas.) When accompanied by a decrease in the circulating platelets, it is called thrombocytopenic purpura; when there is no decrease in the platelet count, it is called nonthrombocytopenic purpura. adj., adj purpu´ric.

There are two general types of thrombocytopenic purpura: primary or idiopathic, in which the cause is unknown, and secondary or symptomatic, which may be associated with exposure to drugs or other chemical agents, systemic diseases such as multiple myeloma and leukemia, diseases affecting the bone marrow or spleen, and infectious diseases such as rubella (German measles).
Symptoms. The outward manifestations and laboratory findings of primary and secondary thrombocytopenic purpura are similar. There is evidence of bleeding under the skin, with easy bruising and the development of petechiae. In the acute form there may be bleeding from any of the body orifices, such as hematuria, nosebleed, vaginal bleeding, and bleeding gums. The platelet count is below 100,000 per cubic millimeter of blood and may go as low as 10,000 per cubic millimeter (normal count is about 250,000 per cubic millimeter). The bleeding time is prolonged and clot retraction is poor. Coagulation time is normal.
Treatment. Differential diagnosis is necessary to determine the type of purpura present and to eliminate the cause if it can be determined. General measures include protection of the patient from trauma, elective surgery, and tooth extractions, any one of which may lead to severe or even fatal hemorrhage. In the thrombocytopenic form, corticosteroids may be administered when the purpura is moderately severe and of short duration. Splenectomy is indicated when other, more conservative measures fail and is successful in a majority of cases. In some instances, especially in children, there may be spontaneous and permanent recovery from idiopathic purpura. (See Atlas 2, Part Q.)
allergic purpura (anaphylactoid purpura) Henoch-Schönlein purpura.
annular telangiectatic purpura a rare form in which pinpoint reddened lesions coalesce to form a ring-shaped or continuously linked pattern, commonly beginning in the lower extremities and becoming generalized. Called also Majocchi's disease.
fibrinolytic purpura purpura associated with increased fibrinolytic activity of the blood.
purpura ful´minans a form of nonthrombocytopenic purpura seen mainly in children, usually after an infectious disease, marked by fever, shock, anemia, and sudden, rapidly spreading symmetrical skin hemorrhages of the lower limbs, often associated with extensive intravascular thromboses and gangrene.
purpura hemorrha´gica primary thrombocytopenic purpura.
Henoch's purpura a type of Henoch-Schönlein purpura in which abdominal symptoms predominate.
Henoch-Schönlein purpura a type of nonthrombocytopenic purpura, of unknown cause but thought to be due to a vasculitis; it is most often seen in children and is associated with clinical symptoms such as urticaria and erythema, arthritis and other joint diseases, gastrointestinal symptoms, and renal involvement. Called also Schönlein-Henoch purpura or syndrome and allergic or anaphylactoid purpura.
idiopathic thrombocytopenic purpura thrombocytopenic purpura not directly associated with any definable systemic disease, although it often follows a systemic infection; the cause is thought to be an IgG immunoglobulin that acts as an antibody against platelets, causing ecchymoses, petechiae, and other bleeding. There are both acute and chronic forms: the acute form has a sudden onset, is more common in children, and usually resolves spontaneously within a few months; the chronic form has a slower onset, is more common in adults, and may be recurrent.
nonthrombocytopenic purpura purpura without any decrease in the platelet count of the blood. In such cases the cause is either abnormal capillary fragility or a clotting factor deficiency.
Schönlein purpura a type of Henoch-Schönlein purpura in which articular systems predominate; called also Schönlein's disease.
Schönlein-Henoch purpura Henoch-Schönlein purpura.
purpura seni´lis dark purplish red ecchymoses occurring on the forearms and backs of the hands in the elderly.
thrombocytopenic purpura purpura associated with a decrease in the number of platelets in the blood; see purpura.
thrombotic thrombocytopenic purpura a form of thrombotic microangiopathy characterized by thrombocytopenia, hemolytic anemia, bizarre neurological manifestations, uremia (azotemia), fever, and thromboses in terminal arterioles and capillaries; some authorities consider it identical to the hemolytic uremic syndrome. Called also microangiopathic hemolytic anemia and Moschcowitz's disease.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

al·ler·gic pur·pu·ra

nonthrombocytopenic purpura due to hypersensitivity to foods, drugs, and insect bites.
Synonym(s): anaphylactoid purpura (1)
Farlex Partner Medical Dictionary © Farlex 2012

allergic vasculitis

A form of nonthrombocytopenic purpura due to a hypersensitivity vasculitis associated with urticaria, erythema, arthritis, gastrointestinal symptoms and renal involvement.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

al·ler·gic pur·pu·ra

(ă-lĕr'jik pŭr'pyŭr-ă)
Nonthrombocytopenic purpura due to sensitization to foods, drugs, and insect bites.
Synonym(s): anaphylactoid purpura (1) .
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

Allergic Purpura

DRG Category:813
Mean LOS:5 days
Description:MEDICAL: Coagulation Disorders

Allergic purpura is an allergic reaction that leads to acute or chronic inflammation of the vessels of the skin, joints, gastrointestinal (GI) tract, and genitourinary (GU) tract. It occurs as an acquired, abnormal immune response to a variety of agents that normally do not cause allergy, and it is manifested by bleeding into the tissues, organs, and joints, which leads to organ dysfunction, discomfort, and immobility. An acute attack of allergic purpura can last for several weeks, but usually episodes of the disease subside without treatment within 1 to 6 weeks. Patients with chronic allergic purpura can have a persistent and debilitating disease. The most severe complications are acute glomerulonephritis and renal failure. Hypertension often complicates the course, and if bleeding is excessive, the patient can develop a fluid volume deficit. On rare occasions, patients may be at risk for airway compromise from laryngeal edema.


Allergic purpura occurs in response to agents such as bacteria, drugs, food, or bee stings. The allergic reaction, probably an autoimmune response directed against the vessel walls, may be triggered by a bacterial infection. Most patients have experienced an upper respiratory infection, particularly a streptococcal infection, 1 to 3 weeks prior to the development of allergic purpura. Experts suggest that other causes, such as allergic reactions to drugs and vaccines, insect bites, and foods (wheat, eggs, chocolate, milk) may lead to the condition.

Genetic considerations

Over 20 genes have been associated with the development of allergy, and mutations of these may be passed on in families. Family studies indicate that if both parents suffer from allergies, the allergy risk in their offspring is 80%. Implicated genes include the IL-4, IL-4 receptor, INF-γ, β-adrenergic receptor, 5 lipoxygenase, PHF1, TARC, and leukotriene C4 synthetase genes. Some alleles of the MEFV and ACE genes along with various HLA alleles are also associated with allergic purpura.

Gender, ethnic/racial, and life span considerations

Allergic purpura can occur at any age, but it is most common in children between 3 and 10 years old; the condition is more common in males than in females. In North America, the disease occurs mostly from November to January. In one-half to two-thirds of children, an upper respiratory tract infection precedes the clinical onset by 1 to 3 weeks, and children are mildly ill with a fever. Whites are more affected than blacks/African Americans.

Global health considerations

No data are available.



Approximately one to two out of four patients with allergic purpura have GU symptoms such as dysuria and hematuria. Other symptoms include headaches; fever; peripheral edema; and skin lesions accompanied by pruritus, paresthesia, and angioedema (swelling of the skin, mucous membranes, or organs). Other patients describe severe GI symptoms (spasm, colic, constipation, bloody vomitus, bloody stools) and joint pain.

Physical examination

Inspect the patient’s skin for the typical skin lesions—patches of purple macular lesions of various sizes that result from vascular leakage into the skin and mucous membranes. These lesions most commonly occur on the hands and arms. Note that in children, the lesions more commonly start as urticarial areas that then expand into hemorrhagic lesions. Determine if the patient has any peripheral swelling, particularly in the hands and face. Perform gentle range of motion of the extremities to determine the presence and location of joint pain. Assess the color of the patient’s urine and stool, and note any bleeding.


The patient may experience a disturbance in body image because of the disfigurement caused by the rash and swelling. Determine the patient’s response to her or his appearance and identify whether the changes interfere with implementing various roles, such as parenting or work.

Diagnostic highlights

No single laboratory test identifies allergic purpura. Supporting tests include complete blood count, erythrocyte sedimentation rate, urinalysis, blood urea nitrogen, creatinine, and coagulation profile.

Primary nursing diagnosis


Impaired skin integrity related to damage and inflammation of vessels


Tissue integrity: Skin and mucous membranes; Wound healing; Body image


Skin surveillance; Wound care; Body image enhancement

Planning and implementation


The treatment prescribed is based on the acuity and severity of the symptoms. Some patients are treated pharmacologically with corticosteroids to relieve edema and analgesics to manage joint and GI discomfort. Allergy testing to identify the provocative allergen is usually performed. If the allergen is a food or medication, the patient needs to avoid ingesting the allergen for the rest of his or her life. Patients who are placed on corticosteroids or immunosuppressive therapy need an environment that protects them as much as possible from secondary infection. If the patient is on corticosteroids, monitor her or him for signs of Cushing’s syndrome and the complications of corticosteroids, such as labile emotions, fluid retention, hyperglycemia, and osteoporosis.

Pharmacologic highlights

Medication or Drug ClassDosageDescriptionRationale
GlucocorticoidsVaries by drugCorticosteroidRelieve edema and analgesics to manage joint and GI discomfort
AzathioprineVaries by age and whether it is initial or maintenance doseImmunosuppressantSuppresses cell-mediated hypersensitivity


If the patient has alterations in coagulation, create a safe environment to prevent bleeding from falls or other injuries. Protect open or irritated skin lesions from further tissue trauma and infection. Apply unguents and soothing creams, if appropriate, to manage discomfort. Assist the patient with colloidal baths and activities of daily living if joint pain and the lesions give the patient limited activity tolerance. Reassure the patient that the lesions are of short duration prior to healing. Explore possible sources of the allergy. Allow the patient time to discuss concerns about the disease. If the patient or significant other appears to be coping ineffectively, provide a referral to a clinical nurse specialist or counselor.

Evidence-Based Practice and Health Policy

Watson, L., Richardson, A. R., Holt, R. C., Jones, C., & Beresford, M. W. (2012). Henoch Schonlein Purpura―a 5-year review and proposed pathway. PLoS One, 7(1), e29512. Online publication. doi 10.1371/journal.pone.0029512

  • Investigators conducted a cohort study to explore the presentation of allergic (Henoch Schonlein) purpura, in which 102 children were diagnosed (incidence was 6.21 cases per 100,000 children in this cohort).
  • Among the children diagnosed with allergic purpura, 100% presented with a palpable rash, 45% presented with arthralgia, 19% presented with joint swelling, 9% presented with abdominal pain, and 5% presented with hyperthermia.
  • Hypertension was present in 14% of patients, of which 28% had proteinuria and 7% had both proteinuria and hematuria. Additionally, 46% of the diagnosed children had initial renal inflammation.
  • The presence of proteinuria at day 7 postdiagnosis had a positive predictive value of 32% (95% CI, 15% to 55%) and a negative predictive value of 97% (95% CI, 90% to 99%) in identifying children at risk for renal complications, including nephritis.

Documentation guidelines

  • Extent, location, and description of erythema; degree of discomfort; signs of wound infection; presence and description of edema
  • Response to allergy testing and withdrawal of the provocative agent if identified
  • Response to treatments: Medications, creams, and colloidal baths
  • Emotional response to the condition; problems coping; body image disturbance

Discharge and home healthcare guidelines

Teach the patient about the disease and its cause. If the allergen is identified, assist the patient in eliminating the allergen if possible. Teach the patient to protect lesions from additional trauma by wearing long-sleeved blouses or shirts. Teach the patient to pay particular attention to edematous areas where skin breaks down easily if injured. Encourage the patient to prevent secondary infections by avoiding contact with others and by using good hand-washing techniques. Encourage the patient to report recurrent signs and symptoms, which are most likely to occur 6 weeks after the initial onset of symptoms.

Provide the patient with information about the medications, including dosage, route, action, and side effects. Provide the patient with written information so that the patient can refer to it for questions at home.

Diseases and Disorders, © 2011 Farlex and Partners

al·ler·gic pur·pu·ra

(ă-lĕr'jik pŭr'pyŭr-ă)
Nonthrombocytopenic purpura due to hypersensitivity to foods, drugs, and insect bites.
Synonym(s): anaphylactoid purpura (1) .
Medical Dictionary for the Dental Professions © Farlex 2012