Free

E-newsletter

Subscribe to Housecall

Our weekly general interest
e-newsletter keeps you up to date on a wide variety of health topics.

Sign up now

Tests and diagnosis

By Mayo Clinic staff

Physical exam
To rule out other possible conditions — such as a respiratory infection or chronic obstructive pulmonary disease (COPD) — your doctor will do a physical exam and ask you questions about your signs and symptoms and about any other health problems.

Tests to measure lung function
You may also be given lung (pulmonary) function tests to determine how much air moves in and out as you breathe. These tests may include:

  • Spirometry. This test estimates the narrowing of your bronchial tubes by checking how much air you can exhale after a deep breath and how fast you can breathe out.
  • Peak flow. A peak flow meter is a simple device that measures how hard you can breathe out. Lower than usual peak flow readings are a sign your lungs may not be working as well and that your asthma may be getting worse. Your doctor will give you instructions on how to track and deal with low peak flow readings.

Lung function tests often are done before and after taking a bronchodilator (brong-koh-DIE-lay-tur), such as albuterol, to open your airways. If your lung function improves with use of a bronchodilator, it's likely you have asthma.

Additional tests
Other tests to diagnose asthma include:

  • Methacholine challenge. Methacholine is a known asthma trigger that, when inhaled, will cause mild constriction of your airways. If you react to the methacholine, you likely have asthma. This test may be used even if your initial lung function test is normal.
  • Nitric oxide test. This test, though not widely available, measures the amount of the gas, nitric oxide, that you have in your breath. When your airways are inflamed — a sign of asthma — you may have higher than normal nitric oxide levels.
  • Imaging tests. A chest X-ray and high-resolution computerized tomography (CT) scan of your lungs and nose cavities (sinuses) can identify any structural abnormalities or diseases (such as infection) that can cause or aggravate breathing problems.
  • Sputum eosinophils. This test looks for certain white blood cells (eosinophils) in the mixture of saliva and mucus (sputum) you discharge during coughing. Eosinophils are present when symptoms develop and become visible when stained with a rose-colored dye (eosin).
  • Provocative testing for exercise and cold-induced asthma. In these tests, your doctor measures your airway obstruction before and after you perform vigorous physical activity or take several breaths of cold air.

How asthma is classified
To classify your asthma severity, your doctor considers your answers to questions about symptoms (such as how often you have asthma attacks and how bad they are), along with the results of your physical exam and diagnostic tests.

Determining your asthma severity helps your doctor choose the best treatment. Asthma severity often changes over time, requiring treatment adjustments.

Asthma is classified into four general categories:

Asthma classificationSigns and symptoms
Mild intermittent Mild symptoms up to 2 days a week and up to 2 nights a month
Mild persistent Symptoms more than twice a week, but no more than once in a single day
Moderate persistent Symptoms once a day and more than 1 night a week
Severe persistent Symptoms throughout the day on most days and frequently at night
Treatments and drugs Preparing for your appointment
References
  1. What is asthma? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/asthma/. Accessed March 14, 2012.
  2. McPhee SJ, et al. Current Medical Diagnosis & Treatment 2012. 51st ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/content.aspx?aID=2740. Accessed March 14, 2012.
  3. Parker MJ. Asthma. Otolaryngologic Clinics of North America. 2011;44:667.
  4. Asthma action plan. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/public/lung/asthma/asthma_actplan.htm. Accessed March 14, 2012.
  5. Longo DL, et al. Harrison's Online. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/content.aspx?aID=9127709. Accessed March 14, 2012.
  6. Asthma overview — What causes asthma? Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=8&cont=6. Accessed March 13, 2012.
  7. Bjerg A. A strong synergism of low birth weight and prenatal smoking on asthma in schoolchildren. Pediatrics. 2011;127:e905.
  8. Ferri FF. Ferri's Clinical Advisor 2012: 5 Books in 1. Philadelphia, Pa. : Mosby Elsevier; 2011. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-0-323-05611-3..00010-0--sc0310&isbn=978-0-323-05611-3&sid=1283797418&uniqId=324341161-6#4-u1.0-B978-0-323-05611-3..00010-0--s6435. Accessed March 13, 2012.
  9. Asthma overview — Diagnosis. Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=8&cont=7. Accessed March 13, 2012.
  10. Zafirlukast. Micromedex Healthcare Series. http://www.micromedex.com. Accessed March 14, 2012.
  11. Asthma overview — Treatment. Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=8&cont=8. Accessed March 13, 2012.
  12. Hashimoto S, et al. Current treatment of severe asthma. Clinical and Experimental Allergy. In press. Accessed Mar. 14, 2012.
  13. Allergy overview — Treatment. Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=9&cont=81. Accessed March 13, 2012.
  14. Mason RJ, et al. Murray and Nadel's Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa.: Saunders Elsevier; 2010. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-1-4160-4710-0..00038-9--s0250&isbn=978-1-4160-4710-0&sid=1283802117&uniqId=324341161-7#4-u1.0-B978-1-4160-4710-0..00038-9--s0325. Accessed March 14, 2012.
  15. Indoor air quality and allergies. Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=9&sub=18&cont=233. Accessed March 15, 2012.
  16. Bruton A, et al. The role of breathing training in asthma management. Current Opinion in Allergy and Clinical Immunology. 2011;11:53.
  17. Alternative therapies. Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=8&sub=16&cont=40. March 14, 2012.
  18. Butterbur. Natural Medicines Comprehensive Database. http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=MAYO&s=nd&pt=100&id=649. Accessed March 15, 2012.
  19. Indian frankincense. Natural Medicines Comprehensive Database. http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=MAYO&s=nd&pt=100&id=63. Accessed March 15, 2012.
  20. Pycnogenol. Natural Medicines Comprehensive Database. http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=MAYO&s=nd&pt=100&id=1019. Accessed March 15, 2012.
  21. Fish oil. Natural Medicines Comprehensive Database. http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=MAYO&s=nd&pt=100&id=993. Accessed March 15, 2012.
  22. Li JT (expert opinion). Mayo Clinic, Rochester, Minn. March 22, 2012.
  23. Anderson CF (expert opinion). Mayo Clinic, Rochester, Minn. March 20, 2012.
DS00021 May 26, 2012

© 1998-2013 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "EmbodyHealth," "Enhance your life," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.

  • Reprints
  • Print

  • Share on:

  • Email

Advertisement


Text Size: smaller largerlarger