Summary about Disease
Non-hereditary angioedema (NHA) is a type of angioedema (swelling in the deeper layers of the skin, often around the face, lips, tongue, throat, hands, or feet) that is not caused by a genetic defect. It is usually acquired later in life and is often related to other underlying medical conditions or medication use. Unlike hereditary angioedema (HAE), NHA does not involve a deficiency or dysfunction of the C1 inhibitor protein due to inherited genetic mutations.
Symptoms
Symptoms of NHA are similar to HAE and include:
Swelling of the face, lips, tongue, or throat (most common)
Swelling of the hands, feet, or genitals
Abdominal pain, nausea, vomiting, and diarrhea (if the swelling affects the intestines)
Difficulty breathing or swallowing (if the swelling affects the throat or larynx)
Hoarseness Symptoms usually develop quickly, over a period of minutes to hours.
Causes
The causes of NHA can vary but commonly include:
ACE Inhibitors: These medications, used to treat high blood pressure and heart failure, are a common cause of NHA.
Acquired C1 Inhibitor Deficiency: This rarer form of NHA is often associated with underlying autoimmune disorders (like lupus or rheumatoid arthritis), lymphoproliferative disorders (like lymphoma), or monoclonal gammopathies. In these cases, the body produces antibodies that attack or consume C1 inhibitor.
Estrogen-related: In rare cases, estrogen therapy or oral contraceptives can trigger NHA in some individuals.
Idiopathic: Sometimes the cause is unknown (idiopathic NHA).
Medicine Used
The treatment of NHA focuses on managing acute attacks and preventing future episodes. Medications used may include:
For acute attacks:
Epinephrine: Used for severe reactions involving airway compromise.
Antihistamines: H1 antihistamines (like diphenhydramine or cetirizine) may help reduce swelling. H2 antihistamines (like ranitidine or famotidine) are sometimes used in combination.
Corticosteroids: Medications like prednisone can help reduce inflammation.
C1-INH concentrate: Sometimes used off-label for acquired C1-INH deficiency.
Icatibant: A bradykinin receptor antagonist, can be effective in some cases.
For prophylaxis (prevention):
Discontinuing ACE Inhibitors: If ACE inhibitors are the cause, stopping the medication is the first step.
Danazol or other androgens: In some cases, medications like danazol (a synthetic androgen) may be used to increase C1 inhibitor levels but carries significant side effects.
Tranexamic acid: An antifibrinolytic agent that can help prevent attacks, though it's less effective than treatments for HAE.
Treating Underlying Conditions: If the NHA is secondary to an underlying autoimmune or lymphoproliferative disorder, treatment of that condition is essential.
Is Communicable
No, non-hereditary angioedema is not communicable. It is not caused by an infectious agent and cannot be transmitted from person to person.
Precautions
Precautions for individuals with NHA include:
Avoid known triggers: If the cause is identified (e.g., ACE inhibitors), avoiding the trigger is crucial.
Carry an epinephrine auto-injector: For those at risk of severe attacks, carrying an epinephrine auto-injector (like EpiPen) and knowing how to use it is essential.
Medical alert identification: Wearing a medical alert bracelet or necklace that identifies the condition is important.
Inform healthcare providers: Always inform healthcare providers about your history of angioedema, especially before undergoing any medical procedures.
Have a treatment plan: Work with your doctor to develop a written treatment plan for managing acute attacks.
Avoid potential triggers: Be cautious with new medications or foods, as some individuals may experience reactions.
How long does an outbreak last?
The duration of an angioedema attack can vary. Without treatment, symptoms may last from 24 to 72 hours. With appropriate treatment, symptoms may resolve more quickly, within hours.
How is it diagnosed?
Diagnosis of NHA involves:
Clinical evaluation: A thorough medical history and physical examination.
Exclusion of HAE: Ruling out hereditary angioedema through blood tests, specifically measuring C4 levels and C1 inhibitor function and quantity. In HAE, C4 levels are typically low, and C1 inhibitor levels and/or function are abnormal. In NHA, C4 may be normal or low, but C1 inhibitor function is usually normal (unless it's acquired C1 inhibitor deficiency).
Laboratory tests:
C1 inhibitor functional assay: Measures the activity of C1 inhibitor.
C1q level: Low levels suggest acquired C1 inhibitor deficiency, often associated with autoimmune or lymphoproliferative disorders.
Complete blood count (CBC), comprehensive metabolic panel (CMP), and other tests: To evaluate for underlying medical conditions.
Medication review: A careful review of current medications, especially ACE inhibitors.
Timeline of Symptoms
The timeline of symptoms in NHA is typically:
Rapid onset: Symptoms usually develop rapidly, often within minutes to hours.
Progression: Swelling can worsen over the first few hours.
Peak: Symptoms usually peak within 12-24 hours.
Resolution: Without treatment, symptoms usually resolve within 24-72 hours. With treatment, resolution may occur more quickly.
Important Considerations
Differentiating NHA from HAE is crucial because the treatments are different.
Identifying the underlying cause is important for proper management and prevention.
Airway compromise is a serious risk, and patients should seek immediate medical attention if they experience difficulty breathing or swallowing.
Long-term management may involve ongoing monitoring and treatment of underlying medical conditions.
Patients should be educated about their condition, potential triggers, and emergency management strategies.