Which lab tests are performed in the evaluation of Legionnaires disease?

Updated: Aug 24, 2018
  • Author: Burke A Cunha, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Tests in LD can include the following:

  • Complete blood count (CBC): Look for leukocytosis, left shift

  • Look for elevated ESR

  • Electrolytes: Look for hypophosphatemia and hyponatremia

  • BUN and creatinine: Look for renal failure and dehydration

  • Liver function tests (LFTs): Look for nonspecific LFT abnormalities, which are very common in LD and may help to distinguish it from other atypical pneumonias

  • Look for highly elevated serum ferritin

  • Creatine phosphokinase: Look for elevation indicating rhabdomyolysis, which occasionally is seen in LD; the rhabdomyolysis may be so severe as to cause renal failure

  • Arterial blood gas (ABG): Look for hypoxemia

  • Gram stain: Typically, many leukocytes and a paucity of organisms are observed; if visible, the organisms are small, faintly staining, gram-negative bacilli

  • Sputum Gram stain: Look for increased polymorphonuclear leukocytes and monocytes without bacteria

  • Urinalysis: Look for proteinuria, hematuria, and renal failure


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