What is the role of lab testing in the workup of acute sinusitis?

Updated: Apr 22, 2020
  • Author: Ted L Tewfik, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Some authors have reported on the use of laboratory tests including sedimentation rate, white blood cell counts, and C-reactive protein levels to help diagnose acute sinusitis. [4] These tests appear to add little to the predictive value of clinical findings in the diagnosis.

Cultures are not routinely obtained in the evaluation of acute sinusitis but should be obtained in a patient in intensive care or with immunocompromise, in children not responding to appropriate medical management, and in patients with complications of sinusitis. Because the nose is colonized with multiple nonpathogenic species of bacteria, care must be taken when evaluating culture results. A specific organism is considered pathogenic when more than 104 colony-forming units of the species are grown on culture or when polymorph counts are greater than 5000 cells/mL.

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