Bronchitis Workup

Updated: Mar 24, 2021
  • Author: Jazeela Fayyaz, DO; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Approach Considerations

Bronchitis may be suspected in patients with an acute respiratory infection with cough; yet, because many more serious diseases of the lower respiratory tract cause cough, bronchitis must be considered a diagnosis of exclusion. A complete blood count with differential may be obtained.

Procalcitonin levels may be useful to distinguish bacterial infections from nonbacterial infections. Trials from 2008 and 2009 have shown that they may help guide therapy and reduce antibiotic use. [8, 9]

Sputum cytology may be helpful if the cough is persistent.

Chest radiography should be performed in those patients whose physical examination findings suggest pneumonia. Elderly patients may have no signs of pneumonia; therefore, chest radiography may be warranted in these patients, even without other clinical signs of infection.

Bronchoscopy may be needed to exclude foreign body aspiration, tuberculosis, tumors, and other chronic diseases of the tracheobronchial tree and lungs.

Influenza tests may be useful. Additional serologic tests, such as that for atypical pneumonia, are not indicated.

Spirometry may be useful because patients with acute bronchitis often have significant bronchospasm, with a large reduction in forced expiratory volume in one second (FEV1). This generally resolves over 4-6 weeks.

Laryngoscopy can exclude epiglottitis.

Goblet cell hyperplasia, mucosal and submucosal inflammatory cells, edema, peribronchial fibrosis, intraluminal mucous plugs, and increased smooth muscle are characteristic findings in small airways in chronic obstructive lung disease.


Cultures and Staining

Obtain cultures of respiratory secretions for influenza virus, Mycoplasmapneumoniae, and Bordetella pertussis when these organisms are suspected. Culture methods and immunofluorescence tests have been developed for laboratory diagnosis of C pneumoniaeinfection.

Obtain a throat swab. Culture and gram stain of sputum is often performed, though these tests usually show no growth or only normal respiratory florae. [1]

Blood culture may be helpful if bacterial superinfection is suspected.


Procalcitonin Levels

Procalcitonin is a prohormone of calcitonin and part of a inflammatory cascade in the immune system. Levels have been shown to be elevated in bacterial infections and not in viral or other inflammatory conditions. Studies suggest values of greater than or equal to 0.25 mcg/L in non-ICU patients and levels greater than 0.5 mcg/L in ICU patients may be appropriate to use as cutoffs for initiation of antibiotic therapy. [10] A subsequent drop of at least 80% in levels may be appropriate to use as a guide for discontinuing antibiotics. Additional data suggest using a procalcitonin algorithm reduces antibiotic usage without increasing the risk of complications. [11]