Understanding Differential Diagnosis of COPD

How You're Diagnosed Matters

A long-term cough is one symptom of COPD.
A long-term cough is one symptom of COPD. BSIP/UIG/Getty Images

Remember when you initially went to the doctor with respiratory symptoms and were diagnosed with COPD? Chances are your doctor formed a differential diagnosis of COPD. That's when doctors rule out other potential causes for your symptoms by comparing them, along with your test results, with two or more other diseases. Here's why differential diagnosis of COPD matters and what your doctor might find.

Why is a Differential Diagnosis Important?

Knowing each differential diagnosis that your doctor has eliminated before reaching a conclusion that you have COPD is important because it confirms that the evidence that was used to form your diagnosis was accurate.

Consider writing down the names of the conditions that your doctor rejected. This way, if your treatment is ineffective, you can revisit the list to see if you were possibly misdiagnosed, which is not uncommon with COPD.

Possible Causes for Your Symptoms That Aren't COPD

A diagnosis of COPD should be considered in anyone who complains of shortness of breath (dyspnea), long-term cough and/or sputum production and a history of repeated exposure to noxious stimuli. Having these symptoms could mean you have COPD, but if could also mean you have something else that closely mimics the symptoms of COPD. These are some of the most common potential diagnoses that may be included in a differential diagnosis:

Asthma

One of the most common differential diagnoses of COPD is asthma. In some cases, it is virtually impossible to tell the two apart, which makes management of either disease difficult. Here are some characteristic features of asthma:

  • Onset generally occurs early in life
  • Symptoms vary daily, often disappearing between attacks
  • Familial history of asthma is often present
  • Allergies, rhinitis and/or eczema may accompany diagnosis
  • Airflow limitation is essentially reversible (unlike COPD)

Congestive Heart Failure

Congestive heart failure (CHF) is a condition that occurs when the heart is unable to pump blood strongly enough throughout the body to maintain circulation. This causes a backup of fluids in both the lungs and the rest of the body. Symptoms of CHF include dyspnea with activity, cough, weakness and fatigue, all of which are also symptoms of COPD. Featured characteristics of the disease include:

  • Fine crackles at base of lungs when listening with a stethoscope
  • Chest X-ray shows dilation of heart muscle and pulmonary edema
  • Pulmonary function tests show volume restriction, not airflow limitation as seen in COPD

Bronchiectasis

Often caused by recurrent inflammation and infection of the airways, bronchiectasis may be present at birth or a person may be predisposed to it as a result of early childhood diseases, such as pneumonia, measles, influenza or tuberculosis.

Bronchiectasis is considered an obstructive lung disease and may exist alone or with other forms of COPD. Characteristics of bronchiectasis include:

  • Large amounts of sputum
  • Bouts of repeated bacterial infections
  • Coarse crackles heard when listening with stethoscope
  • Chest X-ray shows dilated bronchial tubes and thickened bronchial walls
  • Clubbing of the fingers

Tuberculosis

Tuberculosis (TB) is a highly contagious bacterial infection caused by the organism Mycobacterium tuberculosis. While the bacteria normally affects the lungs, it can spread to other parts of the body as well, including the brain, kidneys, bones and lymph nodes. Because symptoms include weight loss, fatigue, persistent cough, difficulty breathing, thick or bloody sputum and chest pain, it is not surprising to see why this illness would be included in a differential diagnosis of COPD. Some characteristics of TB include:

  • Onset can occur at any age
  • Chest X-ray shows air spaces that are filled with fluid and nodular lesions
  • Microbiology reports confirm presence of Mycobacterium tuberculosis in sputum and/or blood
  • Prevalence of TB within local community

Obliterative Bronchiolitis

Obliterative bronchiolitis is a rare form of bronchiolitis that can be life-threatening. It occurs when the small airways of the lungs, also known as bronchioles, become inflamed, and then compressed and narrowed by scar tissue. Also known as bronchiolitis obliterans, the disease is characterized by airway obstruction and a reduction of FEV1 to as low as 16 percent. Symptoms, like COPD, include dyspnea, cough and wheezing. The disease is characterized as follows:

  • Occurs generally at a young age in nonsmokers
  • Possible history of rheumatoid arthritis or exposure to toxic fumes
  • CT scan shows areas of hypo-density

Diffuse Panbronchiolitis

A severe, progressive form of bronchiolitis, diffuse panbronchiolitis has no known cause and is inflammatory in nature. Similar to COPD, symptoms include dyspnea, wheezing, severe cough and sputum production. If left untreated, diffuse panbronchiolitis may progress to bronchiectasis. Featured characteristics of this type of bronchiolitis include:

  • Primarily occurs in nonsmoking males
  • Most patients also suffer from long-term sinusitis
  • Chest X-ray and CT scan show hyper-inflated lungs and pus and/or fluid-filled lesions

The Takeaway

Because each patient is unique and the course of a disease varies individually, not every illness mentioned above will manifest itself in the same way. This is why it's so important to discuss your symptoms with your health care provider as soon as possible so that a proper diagnosis of COPD can be made or ruled out, if warranted.

Source:

Global Initiative for Obstructive Lung Disease. Pocket Guide to COPD Diagnosis, Management and Prevention. Updated 2009.

Continue Reading