Here's how to diagnose asthma

As an asthma expert for MyAsthmaCentral I get a lot of questions about how to tell if it's asthma, and, if the doctor suspects asthma, what to expect. It was with these type of questions in mind I wrote the following post for MyAsthmaCentral.com.

Is It Asthma? Here's How to Find Out

by Rick Frea Wednesday, January 27, 2010 @MyAsthmaCentral.com
So you or your child are having asthma-like symptoms lately and now you're wondering if it's asthma. You've called a doctor and made an appointment. Now what?

According to "Allergy and Asthma: Practical Diagnosis and Management", asthma can be difficult to diagnose because there are many conditions that mimic asthma. Thus, "There is no specific test for asthma. Rather, one goes through a series of elimination processes until the diagnosis is arrived at."

What follows is what you should expect on the road to diagnosing your asthma:

1. Assessment: A doctor will perform a physical assessment of you. He'll check to see if you're:

• Chest is hyper expanded (very common in child asthmatics)
• Shoulders hunched (also common in children)
• Working hard to breathe
• Lungs are wheezy or diminished or tight (some asthmatics don't wheeze)
• Nasal passages are swollen (sinusitis is common trigger of asthma)
• Skin shows signs of eczema (many asthmatics have this)

2. Medical history: Your doctor will ask you specific questions about your medical history that might cue him into an asthma diagnosis. The following are indicators that you might have asthma:

• Coughing (especially at night)
• Shortness of breath (especially at night)
• Chest tightness
• Productive cough (asthmatics usually have white sputum)
• Other signs and symptoms of asthma (click here)

Asthma for dummies, a great book to keep handy, and the asthma guidelines, note the following as common questions you might be asked:

• Do symptoms differ with the seasons?
• Do symptoms come on fast or slow?
• Are your symptoms worse during the day or night?
• Do you wake up at night with breathing trouble?
• Do symptoms get worse when you have a cold?
• Do symptoms get worse when you exercise?
• Do symptoms get worse when exposed to cold air? Humidity?
• Does smoke, dust mites, pollen, or moldworsen symptoms?
• Have you missed school or work due tosymptoms?

3. Family history: Asthma is considered genetic, so if there is an extensive family history of asthma, then chances are that's what you have. Some doctors diagnose by this alone. That was the case with my daughter. Since I have it and she had symptoms, the diagnosis was made and it was treated swiftly with no costly testing.

If the above information gives your doctor the information he needs, further testing may not be needed. Otherwise, he may need to do further testing, such as those listed here:

1. Allergy testing: 75 percent of asthmatics also have allergies. So, based on your answers to the above questions (and especially in children), your doctor might want you to undergo this testing.

2. Pulmonary Function Test (PFT): This is a series of tests where you blow into a mouthpiece and a Spirometer measures your lung function. This test can tell a doctor if you have obstructed air passages in your lungs and how severe it is. It can also determine if the obstruction is reversible. Since asthma is a reversible obstructive airway disease, this test can be very helpful in diagnosing asthma. To learn all you need to know about PFTs, click here.

3. Bronchoprovocation: If your doctor suspects asthma, yet you are not presently showing symptoms, he may have you breath methacholine (called a methacholine challenge) or have you run on a treadmill to see if this induces bronchospasm. This is done in conjunction with PFTs. A negative result to this test will rule out asthma.

4. Lab tests: Asthma is known to cause an increase in basophils, eosinophils and IgE. A sample of your sputum and blood may be tested to check for these and other chemicals that might indicate you have asthma.

5. X-ray: Asthma is a disease that causes air to be trapped in your lungs, and this can show up on an x-ray as your lungs will appear hyper inflated during a flare up (click here to view this). Likewise, this can rule out other disorders (differential diagnosis) such as pneumonia or cardiac problems that might be causing your symptoms. Note, however, that uncomplicated asthma will not show up on an x-ray.

6. Differential diagnosis: Your doctor will want to rule out other diseases that might be causing your symptoms. When I was a patient at National Jewish as a kid, I had a sweat test to rule out cystic fibrosis, a barium swallow under fluoroscopy to rule our structural abnormalities of mediastinum or cardiovascular abnormalities, a pH probe to rule out acid reflux (GERD), and an EKG done to rule out heart problems.

Other conditions that might mimic asthma are: upper airway obstruction (something stuck in your throat), vocal cord dysfunction, Bronchopulmonary dysplasia, enlarged lymph nodes, cancer, viral infections, sinus infection, COPD, bronchiolitis, pulmonary embolism, pneumonia, recurrent cough not due to asthma, and the use of medicines like beta blockers.

Some of the above tests are a bit uncomfortable, although none are that big of a deal. Spirometry can be tiring, allergy testing itchy, but it's always neat seeing what the results reveal.

Once asthma is diagnosed, you'll want to work with your doctor on finding the best treatment to control it. Likewise, you'll want to work together with your doctor to find an asthma action plan so you know exactly what to do the next time you have an asthma flare up.