Which nonspecific tests are included in the workup for Epstein-Barr virus (EBV) infectious mononucleosis (mono)?

Updated: Sep 20, 2018
  • Author: Burke A Cunha, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Nonspecific tests are as follows:

  • Patients with infectious mononucleosis in the differential diagnoses should have a CBC count with differential and an evaluation of the erythrocyte sedimentation rate (ESR). The CBC count is more useful in ruling out other diagnoses that may mimic infectious mononucleosis than in providing any specific diagnostic information. Because leukocytosis is the rule in infectious mononucleosis, the presence of a normal or decreased WBC count should suggest an alternative diagnosis. Lymphocytosis accompanies infectious mononucleosis, increases during the first few weeks of illness, and then gradually returns to normal. The appearance, peak, and disappearance of atypical lymphocytes follow the same time course as lymphocytosis. Patients with fever, pharyngitis, and lymphadenopathy are likely to have EBV infectious mononucleosis if the relative atypical lymphocyte count is equal to or greater than 20%.

  • Atypical lymphocytes should be differentiated from abnormal lymphocytes. Abnormal lymphocytes are associated with lymphoreticular malignancies, whereas atypical lymphocytes are associated with various viral and noninfectious diseases, as well as drug reactions. Atypical lymphocytes are each different in their morphology as observed on the peripheral smear, whereas abnormal lymphocytes are monotonous in their sameness, which readily permits differentiation on the peripheral smear.

  • Because anemia is so rare with EBV infectious mononucleosis, patients with anemia should undergo workup for another cause of their anemia.

  • Thrombocytopenia not uncommonly accompanies EBV infectious mononucleosis, but it may be present in various other viral illnesses, including in patients with heterophile-negative infectious mononucleosis.

  • An ESR is most useful in differentiating group A streptococcal pharyngitis from EBV infectious mononucleosis. The sedimentation rate is elevated in most patients with EBV infectious mononucleosis, but it is not elevated in group A streptococcal pharyngitis. However, an elevated ESR does not differentiate EBV from the other heterophile-negative causes of infectious mononucleosis, nor does it differentiate infectious mononucleosis from malignancies.

  • Because the liver is uniformly involved in EBV infectious mononucleosis, mild elevation of the serum transaminases is a constant finding in early EBV infectious mononucleosis. Mild increases in the serum transaminases are also a feature of the infectious agents responsible for heterophile-negative infectious mononucleosis. High elevation of the serum transaminases should suggest viral hepatitis. The serum alkaline phosphatase and gamma-glutamyl transpeptidase (GGTP) levels are not usually elevated in individuals with EBV infectious mononucleosis.

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