Diagnosis guide for clinicians

Hereditary angioedema: when to suspect it and what to test

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Hereditary angioedema is a rare autosomal dominant disease of recurrent skin, abdominal and upper airway swelling, most often from C1 inhibitor deficiency or dysfunction.Source WAO/EAACI guideline

Across 8 European countries, the Shire-sponsored Icatibant Outcome Survey found a median delay of 8.5 years from first symptoms to diagnosis.

Source European diagnostic delay study

In a later analysis of the same survey, 44.3% of patients reported at least 1 prior misdiagnosis, most often allergic angioedema or appendicitis.

Source Icatibant Outcome Survey misdiagnosis analysis

1 in 50,000Estimated global frequency of HAE due to C1 inhibitor deficiency or dysfunctionWAO/EAACI guideline

8.5 yearsMedian delay from first symptoms to diagnosis across 8 European countries (Shire-sponsored survey)European diagnostic delay study

Up to 25%Patients with no family history of HAE, per the WAO/EAACI guidelineWAO/EAACI guideline

D84.1ICD-10-CM code, defects in the complement systemNLM ICD-10-CM lookup

Orphanet recordORPHA:91378 ↗

Inheritance

Autosomal dominant

Age of onset

All ages

Prevalence

1 to 9 per 100,000 point prevalence, Europe

Also called

Familial angioneurotic edema, HAE, Hereditary angioneurotic edema, Hereditary bradykinine-induced angioedema, Hereditary non histamine-induced angioedema

Live from Orphanet (INSERM) via Orphadata, licensed CC BY 4.0, data version 2026-06-23.

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Patterns to test Red flags Often mistaken for What to test Family screening ICD-10 codes Once confirmed For the patient

Patterns that should prompt a test for Hereditary angioedema

Each sign below is common on its own, which is why Hereditary angioedema is missed. Published studies describe these combinations as the picture to act on. Rows are ordered from the highest published figure to the lowest, within each kind of measure.

Where testing finds it

Share of each screened or biopsied group found to have Hereditary angioedema, from the cited studies. A bar spans the lowest to the highest published figure.

1
Recurrent angioedema without urticaria
Consecutive patients examined for recurrent angioedema without urticaria at a Milan clinic, 1993 to 2003
C1 inhibitor deficiency explained 197 of 776 cases with adequate data, or 25%, in this clinic series (Zingale 2006).Milan angioedema clinic series
25%

How often diagnosed patients show it

Share of patients already diagnosed who had the finding, in the group named on each row. Groups differ by age and type, so read each row with its group.

1
Erythema marginatum before swelling+A rash first read as urticaria+Recurrent swelling
87 patients followed at the Danish national HAE center
A history of erythema marginatum was found in 56% of 87 Danish patients, and half had seen it misread as urticaria (Rasmussen 2016).Danish erythema marginatum study
56%
2
Swelling labeled allergic angioedema+Abdominal attacks labeled appendicitis or another gastrointestinal disorder
418 patients with HAE type 1 or 2 in the Shire-sponsored Icatibant Outcome Survey
Of 418 patients, 44.3% reported at least 1 prior misdiagnosis, most often allergic angioedema or appendicitis (Zanichelli 2016).Icatibant Outcome Survey misdiagnosis analysis
44.3%
3
Recurrent abdominal attacks with vomiting or diarrhea+No skin swelling yet
153 patients with HAE due to C1 inhibitor deficiency in a German abdominal attack study
In 28% of 153 patients, recurrent abdominal attacks began before any characteristic skin swelling (Bork 2006).Abdominal attack study
28%

Also described, without a comparable figure

Swelling or abdominal attacks starting in childhood or adolescence + Attacks increasing after puberty + Relatives with recurrent swelling: No share for this combination was found; median age at first swelling was 11 years and at diagnosis 19 years (Christiansen 2016).Pediatric onset and delay study
Angioedema after starting an ACE inhibitor: No yield figure was found; WAO/EAACI says these patients should be tested for HAE, since the drug may reveal previously silent disease.WAO/EAACI guideline

These figures describe published study groups. They are not the chance that any one patient has Hereditary angioedema, and bars whose ranges overlap are not in a settled order.

Red flags for Hereditary angioedema

What the cited sources describe, grouped by life stage and organ. Each line links to its source.

Swelling pattern

WAO/EAACI advises suspecting HAE with recurrent skin swelling of the limbs, face or genitals, painful abdominal attacks or laryngeal edema.WAO/EAACI guideline
Swelling without wheals or itching; the US HAEA guideline says HAE is not associated with urticaria or pruritus.US HAEA guideline
Swelling that builds over several hours and, untreated, commonly lasts 3 to 5 days, longer than histamine-mediated angioedema.US HAEA guideline
No response to antihistamines, corticosteroids or epinephrine, which the US HAEA guideline calls an important clue in the history.US HAEA guideline
The same guideline says swelling that persists for weeks or longer is not consistent with HAE.US HAEA guideline

Abdomen

Recurrent, painful abdominal attacks; among 153 patients, vomiting occurred in 73% of attacks and diarrhea in 41%.Abdominal attack study
In 28% of those 153 patients, recurrent abdominal attacks began before any characteristic skin swelling had occurred.Abdominal attack study
WAO/EAACI notes that abdominal attacks may go unrecognized in children, because abdominal pain is common in childhood.WAO/EAACI guideline

Airway

Laryngeal edema made up 0.9% of the 131,110 swelling episodes recorded in 221 patients with C1 inhibitor deficiency.Swelling pattern study
The WAO/EAACI guideline warns that HAE attacks of the upper airways can result in asphyxiation.WAO/EAACI guideline
In children, asphyxia can follow upper airway swelling rapidly, probably because of the small airway diameter, per WAO/EAACI.WAO/EAACI guideline

Skin signs before attacks

Erythema marginatum, an evanescent, nonpruritic macular rash, can come before swelling and may mimic urticaria, per the US HAEA guideline.US HAEA guideline
Among 87 Danish patients, 56% had a history of erythema marginatum, and half of all patients had seen it misread as urticaria.Danish erythema marginatum study
WAO/EAACI reports erythema marginatum as a prodromal sign in 42% to 58% of children with HAE.WAO/EAACI guideline

Onset, course and triggers

Symptoms usually start in childhood or adolescence; half of females have a first attack before age 12 and half of males before 13.WAO/EAACI guideline
In a large cohort studied with the US HAEA, median age at first swelling was 11 years and median age at diagnosis 19.Pediatric onset and delay study
The frequency and severity of attacks often increase after puberty, according to the US HAEA guideline.US HAEA guideline
Estrogen-containing contraceptives or hormone replacement and ACE inhibitors may trigger or increase attacks, per the WAO/EAACI guideline.WAO/EAACI guideline
Other reported triggers include trauma, including dental, medical or surgical procedures, psychological stress, fatigue, febrile illness and the menstrual cycle.WAO/EAACI guideline

Family history

A positive family history raises suspicion, although WAO/EAACI notes it may be absent in up to 25% of patients.WAO/EAACI guideline
WAO/EAACI attributes the disease to a de novo SERPING1 variant in approximately 20% to 25% of patients.WAO/EAACI guideline
In the Shire-sponsored survey, patients with a positive family history were not diagnosed any earlier than those without such a history.European diagnostic delay study

Hereditary angioedema is often mistaken for

Diagnoses patients commonly carry first, and why the sources say they are confused.

First diagnosis	Why it is confused
Allergic angioedema	It was the most common prior misdiagnosis, named by 103 of 185 misdiagnosed patients in the Shire-sponsored Icatibant Outcome Survey.Icatibant Outcome Survey misdiagnosis analysis
Appendicitis	Appendicitis was named by 50 of 185 misdiagnosed patients in the same survey, second only to allergic angioedema.Icatibant Outcome Survey misdiagnosis analysis
Other gastrointestinal disorders	The same survey reported a substantial number of gastrointestinal misdiagnoses besides appendicitis.Icatibant Outcome Survey misdiagnosis analysis
Cholecystitis or another surgical abdomen	Abdominal edema can resemble appendicitis or cholecystitis, and is therefore often treated with unnecessary surgical procedures, a German study reports.German abdominal surgery study
Urticaria	Erythema marginatum is often misdiagnosed as urticaria, and WAO/EAACI notes that chronic urticaria can coexist, so wheals do not exclude HAE.WAO/EAACI guideline
ACE inhibitor angioedema	WAO/EAACI says these patients should be tested for HAE, because attacks after starting an ACE inhibitor may point to previously silent HAE.WAO/EAACI guideline
Acquired C1 inhibitor deficiency	Its basic C1-INH and C4 profile is indistinguishable from HAE type 1; later onset, lymphoma or MGUS and a low C1q point to it.WAO/EAACI guideline
HAE with normal C1 inhibitor or idiopathic angioedema	WAO/EAACI lists both in the differential; normal C1-INH tests do not exclude HAE with normal C1 inhibitor.WAO/EAACI guideline

Codes patients often carry before this diagnosis

For spotting the pattern in a problem list or registry. Descriptions are checked daily against NLM's ICD-10-CM service; this is not coding advice.

Angioneurotic edema T78.3XXA, T78.3XXD, T78.3XXS

Recurrent swelling without wheals is the core presentation that WAO/EAACI says should prompt laboratory testing for HAE.WAO/EAACI guideline

Allergic, idiopathic, other or unspecified urticaria L50.0, L50.1, L50.8, L50.9

WAO/EAACI notes that erythema marginatum is often misdiagnosed as urticaria, which can lead to incorrect treatment.WAO/EAACI guideline

Generalized or unspecified abdominal pain R10.84, R10.9

Recurrent abdominal attacks began before any skin swelling in 28% of patients in a series of 153.Abdominal attack study

Adverse effect of ACE inhibitors, initial encounter T46.4X5A

WAO/EAACI says patients diagnosed with ACE inhibitor angioedema should be tested for HAE.WAO/EAACI guideline

Edema of larynx J38.4

Laryngeal edema is among the presentations that WAO/EAACI lists as reasons to suspect HAE.WAO/EAACI guideline

Testing for Hereditary angioedema, step by step

The testing order the cited guidance describes, by who it applies to. It summarizes published guidance and is not a plan for any one patient.

Anyone with recurrent angioedema

Clinical history
WAO/EAACI lists family history, childhood onset, abdominal pain, airway swelling, no response to antihistamines or steroids, prodromes and absent wheals as suggestive.WAO/EAACI guideline

Anyone suspected of HAE

C4, C1-INH protein and C1-INH function together
WAO/EAACI recommends measuring all 3 in every patient suspected of HAE, noting that combined diagnostic accuracy is higher than any single test.WAO/EAACI guideline
Read the pattern
Type 1 shows low C1-INH protein and function, both under 50% of normal. Type 2 shows normal or raised protein with function under 50%.WAO/EAACI guideline
C4 as a screening test: the US HAEA view
The US HAEA guideline calls serum C4 a useful screen, with sensitivity of 81% to 96% between attacks. It adds that a normal C4 during an attack excludes HAE due to C1-INH deficiency.US HAEA guideline
C4 as a screening test: the WAO/EAACI view
WAO/EAACI says the sensitivity and specificity of C4 are limited, so it is not recommended for screening or as the only diagnostic test.WAO/EAACI guideline

Patients with positive or inconsistent results

Repeat positive results
WAO/EAACI suggests repeating all 3 tests, ideally in a certified laboratory, because infrequent testing in many laboratories risks false results.WAO/EAACI guideline

Patients with an uncertain diagnosis

Choice of functional assay
The US HAEA guideline calls the chromogenic C1-INH functional assay more sensitive than ELISA, and stresses proper handling and prompt processing of samples.US HAEA guideline

New angioedema after age 30 without a family history

C1q: the WAO/EAACI threshold
WAO/EAACI advises measuring C1q in this group, reporting it low in 75% of acquired C1-INH deficiency and nearly always normal in HAE.WAO/EAACI guideline

Onset after 40, or with lymphoproliferative or autoimmune disease

C1q: the US HAEA threshold
The US HAEA guideline calls C1q useful here, decreased in 80% of acquired C1-INH deficiency and rarely low in HAE.US HAEA guideline

Selected patients

SERPING1 sequencing
The US HAEA guideline calls sequencing usually unnecessary, reserving it for hereditary versus acquired questions without family history, prenatal requests or repeatedly equivocal results.US HAEA guideline
Limits of SERPING1 sequencing
WAO/EAACI notes that sequencing may miss variants such as those creating cryptic splice sites, and that it helps in mosaicism and genetic counseling.WAO/EAACI guideline

Suspected HAE with normal C1-INH level and function

Normal C1-INH: gene testing
WAO/EAACI recommends testing for variants in F12, ANGPT1, PLG, KNG1, MYOF and HS3ST6, while noting genetic testing identifies only a subset of patients.WAO/EAACI guideline
Normal C1-INH: clinical criteria
Without a variant, US HAEA criteria require a family history of recurrent angioedema and documented failure of high-dose antihistamine for at least 1 month.US HAEA guideline

Children of a parent with HAE

Infants: what WAO/EAACI advises
WAO/EAACI says C4 is not useful before 12 months and cord blood can read falsely low. It advises repeating all early complement tests after age 1.WAO/EAACI guideline
Infants: genetic testing
WAO/EAACI adds that genetic testing increases diagnostic reliability in children when the parent's variant is known and biochemical results are inconclusive.WAO/EAACI guideline
Infants: what the US HAEA advises
The US HAEA guideline says functional C1-INH testing could be considered before age 1. It adds that screening can be done at any age if the family variant is known.US HAEA guideline

Patients diagnosed with ACE inhibitor angioedema

After ACE inhibitor angioedema
WAO/EAACI says these patients should be tested for HAE type 1 and 2, since attacks after starting an ACE inhibitor may reveal previously silent HAE.WAO/EAACI guideline

Where testing goes wrong

Measuring C1-INH protein alone misses type 2, in which protein is normal or raised and only function is low.WAO/EAACI guideline
Median delay was 21 years in type 2 and 8 in type 1, a nonsignificant gap the authors link to protein-only testing.European diagnostic delay study
Complement C3 is expected to be normal in HAE, so WAO/EAACI calls C3 testing unhelpful.WAO/EAACI guideline
Umbilical cord blood can give falsely low complement results, and C4 is often low in healthy infants under 12 months.WAO/EAACI guideline
C1-INH concentrates and anabolic androgens may affect complement test results, according to the US HAEA guideline.US HAEA guideline
Wheals do not exclude HAE, because chronic spontaneous urticaria can coexist, and their absence does not exclude mast cell-mediated angioedema.WAO/EAACI guideline
Danish patients with erythema marginatum had a longer diagnostic delay, which the authors attribute to the rash being misread as urticaria.Danish erythema marginatum study
Abdominal attacks can lead to needless surgery; in a German questionnaire study, patients with HAE were 2.5 times more likely to have abdominal surgery.German abdominal surgery study
Patients misdiagnosed before HAE waited a median of 13.3 years for the diagnosis, against 1.7 years for those never misdiagnosed.Icatibant Outcome Survey misdiagnosis analysis
Laboratories that perform C1-INH tests infrequently risk false positive and false negative results, which WAO/EAACI says repeat testing mitigates.WAO/EAACI guideline
An AAAAI coding summary lists C1 esterase inhibitor deficiency as the inclusion term under D84.1, defects in the complement system.AAAAI immunodeficiency codes

Where to test

C4, C1-INH protein and C1-INH function: These tests are ordered through clinical laboratories, and WAO/EAACI notes that their availability and quality vary around the world. It adds that only skilled laboratories can interpret C1-INH function correctly.WAO/EAACI guideline
NIH Genetic Testing Registry: hereditary angioneurotic edema: Lists laboratory-submitted tests for SERPING1, F12, PLG and ANGPT1, plus broader angioedema and complement panels. The number of tests listed in the registry changes as laboratories add or retire them.NIH GTR
NIH's Genetic Testing Registry listed 46 tests for a search of “Hereditary angioedema” on November 12, 2026. NIH does not endorse or verify the labs it lists.

Family screening and referral

Who else in the family

The US HAEA guideline notes that each child of a patient with HAE has a 50% chance of inheriting it.US HAEA guideline
WAO/EAACI recommends screening grandparents, parents, siblings, children and grandchildren with C1-INH function, C1-INH protein and C4.WAO/EAACI guideline
The US HAEA guideline strongly recommends screening all first-degree relatives because of the inheritance pattern and the clinical risk.US HAEA guideline
WAO/EAACI recommends testing all children of an affected parent as early as possible, and regarding them as affected until HAE is excluded.WAO/EAACI guideline
WAO/EAACI warns that an undiagnosed relative's first attack may affect the airway or abdomen, risking asphyxia or unnecessary surgery.WAO/EAACI guideline
In a survey of 313 patients, only 48% of immediate family members and 26% of extended family members had been tested.US family testing survey
Prenatal diagnosis is uncommon; WAO/EAACI notes the affected parent's SERPING1 variant is not detected in up to 10% of cases.WAO/EAACI guideline
Severity and attack frequency vary widely, even between affected members of the same family, the US HAEA guideline notes.US HAEA guideline

Who to refer to

The WAO/EAACI panel drew on allergology, dermatology, emergency medicine, gastroenterology, hematology, immunology, internal medicine, otolaryngology and pediatrics.WAO/EAACI guideline
The guideline says managing angioedema requires an interdisciplinary approach, and it was supported by the ACARE network of angioedema reference centers.WAO/EAACI guideline
The US HAEA guideline says evaluation by an experienced angioedema specialist may be critical to confirming HAE with normal C1 inhibitor.US HAEA guideline
It adds that a diagnosis of HAE of unknown cause should involve the input of an HAE specialist.US HAEA guideline
WAO/EAACI says pregnant patients with HAE require vigilant care and meticulous monitoring by an HAE expert.WAO/EAACI guideline

Find a specialist by state

From the CMS NPI Registry, a public directory of US clinicians by registered specialty. A listing is not an endorsement and says nothing about experience with Hereditary angioedema; patient organizations and academic centers can often name experienced clinicians.

ICD-10-CM codes for Hereditary angioedema

For orders, referrals and prior authorization. Each code is checked daily against NLM's ICD-10-CM service.

D84.1Defects in the complement systemCurrent in NLM's ICD-10-CM listNLM ICD-10-CM lookup

Once the diagnosis is confirmed

Hereditary angioedema (HAE) drugs for prescribers6 prescribing guides, side by side: Andembry, Dawnzera, Ekterly, Firazyr, Orladeyo, Takhzyro. The page also lists 3 other FDA-approved medicines without a guide yet.Open trials: 14Screen a de-identified patient against every recruiting Hereditary angioedema study on ClinicalTrials.gov.Patient and family pageThe plain-language Hereditary angioedema page, with trials, treatments and help paying.

For the patient: why your doctor ordered this test

Plain language a patient can read or take home.

Your doctor ordered these tests because your swelling attacks could be a sign of hereditary angioedema, often called HAE.

HAE is a rare condition that runs in families and causes swelling of the skin, the belly or the throat.

The swelling usually comes without hives or itching, and allergy medicines usually do not help it.

Simple blood tests check a protein called C1 inhibitor, how well it works, and another protein called C4.

Your doctor may repeat the tests to be sure, because these results can be hard to measure correctly.

Swelling in the throat can make it hard to breathe, and that is always an emergency.

If you have HAE, your parents, brothers, sisters and children can be tested too, even if they feel fine.

Questions clinicians ask about Hereditary angioedema testing

Which combinations of findings should prompt testing for hereditary angioedema?

In published screening and biopsy studies, the highest yields came from recurrent angioedema without urticaria (25% of consecutive patients examined for recurrent angioedema without urticaria at a Milan clinic, 1993 to 2003). Among patients already diagnosed, the most common combination began with erythema marginatum before swelling, seen in 56% of 87 patients followed at the Danish national HAE center. These figures describe study groups, not any one patient's chance of having hereditary angioedema.

What labs should be ordered for suspected hereditary angioedema?

WAO/EAACI recommends measuring C4, C1-INH protein and C1-INH function in every patient suspected of HAE. The US HAEA guideline names the same 3 tests and calls low C4 plus low C1-INH antigen or function consistent with the diagnosis. WAO/EAACI suggests repeating all 3 tests in patients who test positive, to confirm the diagnosis.

Does a normal C4 rule out hereditary angioedema?

Not on its own, according to WAO/EAACI, which says C4 has limited sensitivity and specificity and should not be the only test. The US HAEA guideline reports C4 sensitivity of 81% to 96% between attacks. It adds that a normal C4 during an attack excludes HAE due to C1-INH deficiency.

How do you tell HAE type 1 from type 2?

C1-INH protein separates them, per WAO/EAACI: it is low in type 1 and normal or raised in type 2. C1-INH function is under 50% of normal in both types, per the same guideline. WAO/EAACI puts type 1 at about 85% of HAE due to C1-INH deficiency or dysfunction.

When should C1q be checked in angioedema?

C1q helps separate acquired C1-INH deficiency from HAE, and WAO/EAACI advises it for new angioedema after age 30 without a family history. The US HAEA guideline uses onset after 40, or coexisting lymphoproliferative or autoimmune disease. The 2 guidelines report low C1q in 75% and 80% of acquired cases.

How is HAE with normal C1 inhibitor diagnosed?

Genetic testing is the only laboratory route, and WAO/EAACI recommends testing for F12, ANGPT1, PLG, KNG1, MYOF and HS3ST6 variants. Without a variant, US HAEA criteria require normal C4 and C1-INH tests, a family history of recurrent angioedema and documented failure of high-dose antihistamines.

When can the infant of a parent with HAE be tested?

WAO/EAACI recommends testing children of affected parents as early as possible, then repeating any complement test done before age 1. It says C4 is not useful before 12 months and cord blood can read falsely low. The US HAEA guideline says functional C1-INH testing could be considered earlier, and screening works at any age once the family variant is known.

What is the ICD-10 code for hereditary angioedema?

Hereditary angioedema due to C1 inhibitor deficiency is coded D84.1, defects in the complement system, per the NLM ICD-10-CM lookup checked November 10, 2026. An AAAAI coding summary lists C1 esterase inhibitor deficiency as an inclusion term under D84.1.

Sources

The international WAO/EAACI guideline for the management of hereditary angioedema - The 2021 revision and update. World Allergy Organization Journal 2022;15(3):100627 (Maurer M et al; funded by WAO and EAACI, many panel members report industry ties; also published in Allergy 2022), via PubMed Central, 2022-04-07.
US HAEA Medical Advisory Board 2020 Guidelines for the Management of Hereditary Angioedema. Journal of Allergy and Clinical Immunology: In Practice 2021;9(1):132-150 (Busse PJ et al; US HAEA paid meeting travel, several authors report industry ties), full text via US HAEA, 2020-09-06.
Hereditary angioedema with C1 inhibitor deficiency: delay in diagnosis in Europe. Allergy, Asthma and Clinical Immunology 2013;9(1):29 (Zanichelli A et al; Icatibant Outcome Survey sponsored and funded by Shire), via PubMed Central, 2013-08-12.
Misdiagnosis trends in patients with hereditary angioedema from the real-world clinical setting. Annals of Allergy, Asthma and Immunology 2016;117(4):394-398 (Zanichelli A et al; 2 authors are Shire employees), via PubMed abstract, 2016-10.
Pediatric Hereditary Angioedema: Onset, Diagnostic Delay, and Disease Severity. Clinical Pediatrics 2016;55(10):935-942 (Christiansen SC et al, with US HAEA authors), via PubMed abstract; funding and disclosures not seen, 2015-11-18.
Hereditary angioedema: new findings concerning symptoms, affected organs, and course. American Journal of Medicine 2006;119(3):267-274 (Bork K et al), via PubMed abstract; funding and disclosures not seen, 2006-03.
Symptoms, course, and complications of abdominal attacks in hereditary angioedema due to C1 inhibitor deficiency. American Journal of Gastroenterology 2006;101(3):619-627 (Bork K et al), via PubMed abstract; funding and disclosures not seen, 2006-02-08.
Urticaria and Prodromal Symptoms Including Erythema Marginatum in Danish Patients with Hereditary Angioedema. Acta Dermato-Venereologica 2016;96(3):373-376 (Rasmussen ER et al), via PubMed abstract; funding and disclosures not seen, 2016-03.
Is there a need for clinical guidelines in the United States for the diagnosis of hereditary angioedema and the screening of family members of affected patients?. Annals of Allergy, Asthma and Immunology 2010;104(3):211-214 (Lunn ML et al), via PubMed abstract; funding and disclosures not seen, 2010-03.
Unnecessary abdominal interventions in patients with hereditary angioedema. Journal der Deutschen Dermatologischen Gesellschaft 2018;16(12):1443-1449 (Hahn J et al), via PubMed abstract; funding and disclosures not seen, 2018-11-21.
Immunodeficiencies Disease Codes, ICD-10-CM and ICD-9-CM. American Academy of Allergy, Asthma and Immunology, practice management coding sheet, 2017-03.
NIH Genetic Testing Registry tests for hereditary angioneurotic edema, concept C0019243 (listings checked through NCBI E-utilities on November 10, 2026). National Center for Biotechnology Information, NIH, 2026-11-10.
ICD-10-CM search results for "D84.1" (Clinical Table Search Service). National Library of Medicine, 2026-11-10.
Angioedema without urticaria: a large clinical survey. CMAJ 2006;175(9):1065-1070 (Zingale LC et al), via PubMed abstract; funding and disclosures not seen, 2006-10-24.

A reference for licensed professionals, checked against its sources on November 10, 2026. It summarizes what the cited guidance says and does not tell anyone how to diagnose or treat a specific patient. Guidelines change; the current guideline and the treating clinician's judgment govern. Trial Friend is an independent information service, not a medical provider.