Pneumonia laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]
Overview
Laboratory Tests
Routine Tests
Findings in routine blood tests are based on the severity of the disease and the cause, they can include the following:[1]
- Leukocytosis with left shift (in cases of bacterial pneumonia)
- Leukopenia (in cases of atypical pneumonia)
- Eosinophilia (in cases of eosinophilic pneumonia)
- Anemia
- Hyponatremia
- Thrombocytopenia
- Elevated BUN
- Findings of lactic acidosis (decreased HCO3, increased lactic acid levels)
Sputum Gram Stain and Culture
- Sputum samples should be obtained of all patients with productive cough.
- Gram-stain and culture should be performed to assess the causative agent and guide the therapy.
- In more than 80% of cases of pneumococcal pneumonia the sputum culture is positive.[2]
Blood Culture
- Blood culture may be positive in cases of hematogenous spread, such as S. aureus pneumonia, and in around one fourth of patients with pneumococcal pneumonia.
Other Laboratory Tests
Urine Antigen Test [3]
- Used to diagnose Legionella disease.
- The presence of the antigen in urine can be detected in 24 hours since the onset of the symptoms
- The severity of Legionella disease increases the sensitivity of the urinary antigen test.
References
- ↑ Solomon, Caren G.; Wunderink, Richard G.; Waterer, Grant W. (2014). "Community-Acquired Pneumonia". New England Journal of Medicine. 370 (6): 543–551. doi:10.1056/NEJMcp1214869. ISSN 0028-4793.
- ↑ Musher, Daniel M.; Thorner, Anna R. (2014). "Community-Acquired Pneumonia". New England Journal of Medicine. 371 (17): 1619–1628. doi:10.1056/NEJMra1312885. ISSN 0028-4793.
- ↑ Couturier MR, Graf EH, Griffin AT (2014). "Urine antigen tests for the diagnosis of respiratory infections: legionellosis, histoplasmosis, pneumococcal pneumonia". Clin Lab Med. 34 (2): 219–36. doi:10.1016/j.cll.2014.02.002. PMID 24856525.