What is the role of lab testing in the diagnosis of diskitis?

Updated: May 13, 2020
  • Author: Alvin Marcovici, MD; Chief Editor: Jeffrey A Goldstein, MD  more...
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Elevations in the erythrocyte sedimentation rate (ESR) and the C-reactive protein (CRP) level are the most consistent laboratory abnormalities seen in cases of diskitis. The mean ESR for patients with diskitis is 85-95 mm/hr. The utility of the ESR can be extended by performing serial measurements during treatment. A 50% decline in the ESR can usually be expected with successful treatment, and the ESR often continues to decline after treatment. Frequently, the ESR may not return to normal levels despite adequate therapy.

Leukocytosis is often present in systemic disease but is frequently absent in diskitis cases. Diskitis is generally accompanied by a normal peripheral white blood cell (WBC) count if the primary site of infection has been treated.

Procalcitonin (PCT) has been evaluated as a diagnostic tool and monitoring parameter for spondylodiskitis and for discrimination between bacterial infection and aseptic inflammation of the spine, but a study by Maus et al did not find it to be useful for these purposes. [7]  A study by Jeong et al found serum PCT to be less sensitive than serum CRP in patients with spinal infection. [8]

Blood cultures must be obtained on a frequent basis for any patient suspected of harboring an infected disk. Appropriate therapy may be instituted for positive blood cultures without the need for invasive tests. Unfortunately, blood cultures are positive in only one third to one half of diskitis cases.

Sputum and urine cultures are necessary to locate any other sources of infection, including respiratory and genitourinary sites.

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