Pediatric Angioedema Workup

Updated: Jun 23, 2022
  • Author: Shih-Wen Huang, MD; Chief Editor: Harumi Jyonouchi, MD  more...
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Approach Considerations

The diagnostic workup for urticaria-related angioedema is the same for urticaria. Perform an immunoglobulin E (IgE) antibody skin test or radioallergosorbent test (RAST) if the history is suggestive of a rash caused by foods, drugs, insect venom, or latex.

Obtain a bacterial culture with sensitivity if the patient has a history of fever and sore throat.

Obtain a thyroid profile, antithyroid microsomal antibodies, and antithyroglobulin antibody if the patient has a strong family history of thyroid disorder or symptoms of hypothyroidism; this is more frequent in females. However, patients are often euthyroid.

Measure C1 inhibitor (C1INH) and C3 and C4 levels if the patient has a family history of angioedema.

Obtain stool for ova and parasites if the patient reports ingestion of poorly cooked meats or travel in unsanitary areas.

Perform antinuclear antibody testing and urinalysis with microscopic examination if the patient may have arthritis, photosensitivity, or other signs or symptoms of collagen vascular disease.

Obtain a complete blood cell count (CBC) with differential, C-reactive protein level, and erythrocyte sedimentation rate if the patient's history indicates underlying vasculitis or inflammatory diseases.


Other Tests

Acquired angioedema (AAE) is characterized by low functional C1INH levels, low C4 levels, and C3 levels within the reference range. Concentration of C1q is often very low.

Plasma levels for the diagnosis of hereditary angioedema (HAE) include the following:

  • C4 level less than 14 mg/L (diagnostic)

  • C1q level greater than 77 mg/L

  • C1INH (antigenic) level less than 199 mg/L (diagnostic)

  • C1INH (functional) level less than 72% of the reference range (diagnostic)

The summary of complement profiles in different forms of angioedema is as follows:

  • HAE1: C1INH levels are low; C4 levels are almost always low and can be used as the first step of screening; C1, C3, and C1q levels are all within the reference range. These changes are seen in both hereditary and spontaneous mutation conditions.

  • HAE2: C1INH levels may be normal or elevated but are dysfunctional; C1, C3, and C1q levels are within the reference range, but C4 levels are almost always low.

  • HAE3: The complement profile is normal.

  • AAE1: C1INH and C4 levels are low. C1q levels are usually, but not always, reduced.

  • AAE2: The findings are the same as in AAE1. Autoantibody testing may be appropriate.

  • Idiopathic angioedema: The complement profile is normal.

  • Nonhistaminergic angioedema (INAE): The complement profile is normal.

  • Allergic angioedema: The complement profile is normal.

  • ACE inhibitor–induced angioedema: The complement profile is normal.

Prothrombin fragment (F1 + 2) and D-dimer levels may have an important diagnostic value. A study in 28 patients with C1INH deficiency during acute attacks and remission, in 35 patients without C1INH deficiencies during abdominal colic, and in 20 healthy subjects found high levels of these biomarkers during acute angioedema attacks in patients with C1INH deficiency. [19]



Ultrasonography of the GI tract may help differentiate between HAE and conditions of surgical abdomen.

In hereditary angioedema, ascites and edema of the intestinal walls are present in more than 80% of patients during acute attacks.