Approach to Urticaria: History and investigations
Classification of urticaria according to duration
Acute urticaria : Urticaria is considered acute when it has been present for less than six weeks.
Chronic urticaria — Urticaria is considered chronic when it is recurrent, with signs and symptoms recurring most days of the week, for six weeks or longer.
Chronic urticaria classification
- Chronic spontaneous urticaria (CSU).
- Chronic inducible urticaria (Physical urticaria).
Clinical criteria of urticarial lesions
- Pruritic transient wheals that disappear within 24 hours.
- Not painful.
- Disappear without leaving pigmentation.
- If lasts more than 24 and are painful you should exclude urticarial vasculitis.
- May be associated or not with angioedema.
- In case of angioedema without urticaria, others causes of angioedema should be excluded.
It is critical to exclude anaphylaxis. Anaphylaxis may be fatal. in anaphylactic reactions, itching, flushing and pruritus in palms and soles in addition to generalized urticaria and angioedema are followed by respiratory symptoms and by GIT symptoms.
Signs and symptoms of anaphylaxis
- Skin and mucous membranes: Urticaria and angioedema.
- Respiratory : change of voice, hoarseness of voice, chest tightness, wheezing, cough
- Gastrointestinal : nausea, vomiting and abdominal pain.
- Cardiovascular : hypotension, dizziness, tachycardia.
Voice change may be the earliest sign of laryngeal edema.
History taking in a patient with urticaria
The aim of taking history is to:
- Define the types of urticaria (acute or chronic).
- Exclude associated systemic conditions.
- Recognize any triggering factor.
- Exclude anaphylaxis.
General questions to ask
- Ask about manifestation of anaphylaxis
- Chest tightness or difficulty in breathing.
- Change of voice or hoarseness o voice.
- Nausea, vomiting, abdominal pain.
- Dizziness.
- Ask about the duration, to decide the type of urticaria
- Acute urticaria: present less than 6 weeks.
- Chronic urticaria: present more than 6 weeks.
- Ask about previous episodes of urticaria.
- Ask about joint pain, fever, weight loss or other signs of diseases associated with urticaria.
- Ask about past or family history of angioedema.
Acute urticaria questions
- Ask about recent viral or bacterial infections (fever, cough, sore throat, nausea, vomiting, diarrhea).
- Ask about recent use of drugs (Antibiotics – NSAIDs – supplements – other drugs).
- Ask about manifestations of systemic diseases (fever-weight loss-bone pain- joint pain)
- Ask about recent history of travel (parasitic infections).
- Ask about recent contact with pets.
- Ask about recent eating of sea food, sushi, nuts, chocolate, cheese.
- Ask about recent using of new skin care products(lotion, cream, hair dye, perfumes, etc)
- Ask about recent contact with new clothes.
- Ask about pregnancy.
- Ask about doing exercise hours before urticaria.
- Ask about recent history of insect bites or stings.
- Ask about history of radiocontrast medium exposure.
- Ask the patient if it is induced by heat, cold, pressure or vibration.
- Ask about transfusion history.
Chronic urticaria questions
- Ask about history of drugs.
- Ask about history of infections.
- Ask about manifestations of systemic diseases (fever, weight loss, arthralgias, arthritis, cold or heat sensitivity, abdominal pain, and bone pain).
- Ask about history of atopy.
- Ask about sexual history.
- Ask about psychological stress.
- Ask about diet changes (spicy food- alcohol). Food allergy is rare in chronic spontaneous urticaria.
- Ask about physical urticarias( heat, cold, exercise, pressure, water, vibration, sunlight).
- Ask about relationship to the menstrual cycle (urticaria may rarely appear 7–10 days before menstruation).
What are the findings that may be detected by examination ?
- Dermatological examination
- Urticarial wheals : the individual lesions usually disappear within 24 hrs.
- Angioedema.
- Normal skin : wheals may be absent during the time of examination, you can show your patient urticaria pictures to help him recognizing the condition. you can also ask your patient to take pictures by his phone for the skin lesions.
- Vital signs to exclude anaphylaxis.
- General examination : eyes, ears, nose, throat, lymph nodes, abdomen, and musculoskeletal system to exclude any underlying cause.
- Testing for dermatographism : using the blunt end of a pen.
Urticarial and figured erythemas are common prodromal eruptions in Bullous pemphigoid.
Is it essential to ask for investigations in case of acute urticaria?
It depends on history taking and examination findings. If no systemic disease is suspected and if urticarial vasculitis is excluded, Investigations are not recommended. Most patients with antihistamine-responsive urticaria do not need an extensive investigation.
What are the investigations for a patient with acute urticaria?
In patients with acute urticarias, investigations are usually not indicated, but if symptoms persists, initial lab testing may be done.
- Full blood count (FBC) and differential.
- Erythrocyte sedimentation rate (ESR).
- Urine analysis
- Liver function tests.
- ImmunoCAP in case of IgE-mediated reactions to environmental allergens.
- Skin prick testing (patients need to stop anti-histamine treatment (usually for 3 days) prior to having the skin testing and during this time urticarial symptoms may become very severe and may even progress to systemic reactions requiring hospital treatment.)
What are the investigations for a patient with chronic urticaria?
If patient with mild disease and is antihistamine responder, it is not recommended to do investigations.
For patients with severe disease and not showing improvement on antihistamines, investigations are required to exclude systemic conditions.
- CBC with differential.
- Eosinophilia : exclude parasitosis.
- ESR : may be elevated in urticarial vasculitis, lupus erythematosus, macroglobulinaemia or cryopyrin-associated periodic syndromes.
- CRP: may be increased in cryopyrin-associated periodic syndromes.
- TSH, Thyroid autoantibodies (antithyroglobulin, antimicrosomal antibodies, or both), anti-TPO ( thyroid peroxidase)
- Challenge tests : If the history is suggestive of physical urticaria.
- Autologous serum skin test : to exclude autoimmunity.
What is the indication for skin biopsy?
Skin biopsy is indicated if urticarial vasculitis is suspected based on clinical manifestations.
For more details: How to treat acute urticaria
For more details : Acute and Chronic Urticaria: Evaluation and Treatment.
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