Is it difficult to get hereditary angioedema (HAE) diagnosed?
Because HAE is rare, few people have heard of it, including many doctors. That's why getting an accurate diagnosis can be challenging.
In the past, delays in diagnosis ranged from 10 to 22 years. While delays are still common, about 40% of patients are now diagnosed within the first 3 years, while approximately 33% experience delays of 10 years or more.
Misdiagnosis is common
HAE symptoms can look very similar to the symptoms of other, more common conditions. In one survey of 313 people with HAE, up to 65% of the participants had been misdiagnosed with another condition prior to receiving their HAE diagnosis. Most commonly, skin attacks were mistaken for allergic reactions. Abdominal attacks were also confused with appendicitis or irritable bowel syndrome.
If you suffer from symptoms like unexplained swelling or attacks of abdominal pain that last for days, fill out a Doctor Discussion Guide for help talking with your doctor about HAE.
Consequences of misdiagnosis
Misdiagnosis can have consequences ranging from time spent suffering with unexplained symptoms and visiting doctors, to receiving inappropriate treatment and more. In fact, in a survey, 19% of patients underwent an unnecessary surgical procedure as a result of misdiagnosis, including removal of the appendix.*
How is HAE diagnosed?
Of course, getting a diagnosis starts by talking with your doctor. But because most doctors will never see a patient with HAE, they may not be familiar with the condition. So, it’s a good idea for you to be as prepared as possible. Prior to your doctor’s appointment, you can start keeping a journal to record important information, like the location and severity of your attack(s). A journal can also help you keep track of details, like what you were doing and how you were feeling before your attack. Sharing these facts with your doctor can help him or her get a better understanding of your symptoms.
What to expect at your doctor's appointment
If your doctor thinks there's a chance you could have HAE, he or she will likely ask about your symptoms and when you first noticed them. Because HAE is usually passed down through relatives, your doctor will probably ask if anyone in your family has been diagnosed with HAE or experienced swelling episodes.
Remember that you could still have HAE even if no one else in your family has it. One in 4 HAE cases results from a spontaneous change in genetic code, so there may be no family history to help with your diagnosis. Knowing your symptoms can help your doctor decide whether you should be tested for HAE. Filling out your Doctor Discussion Guide can help get your conversation started.
Luckily, my immunologist had seen other people with HAE and ordered blood work. Within 2 weeks, I was diagnosed with HAE.
Confirming the diagnosis
To know for certain that you have HAE, a blood test is recommended. Your doctor will measure your levels of the proteins C4 and C1 esterase inhibitor. If you have HAE, this test can also help determine whether you have Type I or Type II HAE.
Diagnosing HAE with normal C1-INH can be more complicated
Diagnosing HAE with normal C1-INH (previously known as Type III HAE) can be more complicated, because C4 and C1 esterase inhibitor are at normal levels and work the way they should. So, the blood test used to confirm Types I and II can't be used. Instead, a diagnosis is based on other findings, like symptoms, family history, how you respond to certain medications and genetic testing.
Most patients with HAE with normal C1-INH are women. About a quarter of patients have a deficiency of a specific protein called Factor XII. In these patients, similar to HAE Types I and II, attacks are often correlated with changes in estrogen, such as during pregnancy. Testing for mutations in the gene for Factor XII protein is not yet widely available.
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*In a 2010 online survey of 125 United States patients.