Skip to Main Content

++

Make the Diagnosis: Mononucleosis

++

Prior Probability of Mononucleosis

++

Mononucleosis is caused by the Ebstein-Barr virus (EBV) and is most common in children and young adults, but especially between ages 16 and 20. Among those aged 16 to 20 years, the community-based annual incidence rate of mononucleosis is 0.7% to 2.7%.1,2,3 About 1 of 13 adolescents presenting with a sore throat will have mononucleosis (prior probability, 7%).1

++

Population in Whom Mononucleosis Should Be Considered

++

The diagnosis should be considered especially in young adults with sore throat, fever, lymphadenopathy, malaise, and fatigue. Fatigue that is especially pronounced and is excessive for the patient's usual activities can be present. Mononucleosis presents as an acute or chronic illness depending on the phase of disease (chronic symptoms may last months). The differential diagnosis includes other viral illnesses (cytomegalovirus, toxoplasmosis, adenovirus, human immunodeficiency virus), but also acute leukemia.

++

Assessing the Likelihood of Mononucleosis

++

While symptoms describe the clinical picture when mononucleosis is considered as a diagnosis, no studied individual symptom has a positive or negative likelihood ratio (LR) that is diagnostically useful because the CI for all individual symptoms studied has included 1.0. Most patients will have sore throat and/or fatigue (sensitivity range, 0.81–0.83). Physical examination findings combined with simple laboratory parameters dominate the clinical diagnosis. Palatal petechiae has been reported to occur infrequently (5.5%) among patients evaluated for mononucleosis in 1 study, but when present are associated with an LR+ of 5.3 (CI, 2.1–13).1 The presence of posterior cervical adenopathy or splenomegaly is the most useful physical examination finding (see Table 101-1). The absence of any adenopathy is the most useful finding for identifying patients least likely to have mononucleosis.

++
Table Graphic Jump Location
Table 101-1.Useful Findings for Assessing the Likelihood of Mononucelosis
++

Mononucleosis is named for the characteristic mononuclear leukocytosis associated with EBV infections. The presence of atypical lymphocytes ≥ 10% has an LR of 11 (95% CI, 2.7–25), while the presence of atypical lymphocytes at lower percentages of the count reduces the likelihood of mononucleosis (see Table 101-1). The greater the percentage of atypical lymphocytes, the more ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.

Ok

About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

JAMAevidence Full Site: One-Year Subscription

Connect to the full suite of JAMAevidence content and resources including interactive self-assessment, videos, and more.

$495 USD
Buy Now

Pay Per View: Timed Access to all of JAMAevidence

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.