Finding a Zebra in a Crowd of Horses
In medical training, doctors often hear the old adage, “When you hear hoof beats, think horses not zebras!” This concept applies when evaluating and diagnosing patients with what are considered common conditions.
However, sometimes the rare diagnosis is the right one. Dr. Shannon Kasperbauer, an infectious disease physician at National Jewish Health, shares her experience identifying the zebra known as nontuberculous mycobacterial (NTM) lung disease, a chronic and progressive condition.
Looking for the Signs and Risk Factors of NTM Lung Disease
There are many “horses” or common lung diseases that people may be familiar with, such as chronic obstructive pulmonary disorder (COPD) and asthma, but NTM lung disease is a less common “zebra” that, Dr. Kasperbauer advises, at-risk patients should be educated on.
While many may not be familiar with NTM lung disease, everyone comes into contact with NTM bacteria during their daily lives, and certain people are at a greater risk to develop the disease. The most common species of NTM lung disease is called Mycobacterium avium complex or MAC, which accounts for more than 80 percent of all cases in the U.S.
The bacteria can be found in tap water, shower heads, steam from tubs and showers, and soil from parks, gardens and the environment. People can get NTM lung disease when breathing the bacteria in, but most people do not develop the condition because their lungs are healthy enough to clear the bacteria. However, those with pre-existing lung conditions are at greater risk of getting NTM lung disease.
Many of the NTM lung disease patients that Dr. Kasperbauer treats also have other lung conditions, such as:
- Bronchiectasis – when the walls of the airways, or bronchi, become dilated and thickened from chronic inflammation and/or infection, leading to the build-up of mucus
- COPD – a progressive disease that makes it hard to breathe
- Asthma – a lung disease that inflames and narrows the airways
In fact, 50 percent of people with bronchiectasis may have active NTM lung disease. Similarly, people with COPD are almost 16 times more likely to get NTM lung disease. That’s because conditions like these that cause damage to the lungs make it difficult to clear NTM bacteria.
Those susceptible to NTM lung disease include people with weakened immune systems, and it is more common in women than in men. The people most at risk for NTM lung disease are those aged 65 and older, an age group that is expected to nearly double by 2030.
Through her clinical practice, Dr. Kasperbauer understands that there are often delays in NTM lung disease diagnosis.
“NTM lung disease can be difficult to diagnose because it may present differently in each patient. The disease can also masquerade as other lung conditions,” said Dr. Kasperbauer.
Those with NTM lung disease may experience symptoms that are similar to other, more common lung conditions, such as coughing, trouble breathing/shortness of breath and feeling tired often. The symptoms can be so similar, that NTM lung disease is sometimes misdiagnosed or not diagnosed at all. Many people believe their symptoms are due to the lung condition they already have. As a result, people can have NTM lung disease for months, sometimes years, without knowing it.
Diagnosing NTM Lung Disease
According to Dr. Kasperbauer early diagnosis is important.
“Our goal as doctors is to diagnose NTM lung disease patients as early as possible to give them the greatest chance of cure,” she explains.
If a doctor suspects that their patient has NTM lung disease, they may:
- Conduct a physical exam
- Review medical history
- Conduct a sputum culture, where your doctor will ask you to cough up mucus and analyze the mucus for mycobacteria
- Conduct a chest CT scan or X-ray to view the potential damage to your lungs
It’s important to get tested for NTM lung disease and diagnosed early on because the condition can be progressive and chronic. In fact, symptoms can worsen over time, and in some cases, an NTM infection can cause severe, even permanent damage to the lungs.
Learn More About NTM Lung Disease
Dr. Kasperbauer is inspired by each patient who comes into the clinic. Some patients are at the beginning of their journey and have just learned about their diagnosis, while others have been diagnosed for years. Whichever category these patients fall into, there are resources available to help support them at different points in their journey, including those who haven’t been diagnosed yet.
If you think you or a loved one may have NTM lung disease, you can talk to a pulmonologist or infectious disease specialist about getting tested. And visit AboutNTM.com for information about NTM lung disease, including additional tools, support and resources, such as a discussion guide to help prepare for the next doctor’s appointment.
About Dr. Shannon Kasperbauer
Dr. Shannon Kasperbauer is an infectious disease physician and Associate Professor in the Division of Mycobacterial and Respiratory Infections at National Jewish Health in Denver. She is also affiliated with the University of Colorado Hospital and holds professional memberships with the American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA). Dr. Kasperbauer has clinical interests in chronic respiratory infections related to bronchiectasis, such as nontuberculous mycobacteria and tuberculosis.
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