Common Blood Test Can Help Distinguish Between Mononucleosis

CHICAGO, IL -- January 16, 2007 --

Measuring a patient's ratio of white blood cell types may help
physicians to accurately distinguish between the similar conditions
infectious mononucleosis and bacterial tonsillitis, potentially guiding
treatment decisions, according to an article in the January issue of
Archives of Otolaryngology–Head & Neck Surgery, one of the
JAMA/Archives journals.



Acute tonsillitis (inflammation of the tonsils) and infectious
mononucleosis (caused by the Epstein-Barr virus) are both common ear,
nose and throat conditions with similar symptoms, according to
background information in the article. These symptoms include sore
throat, fever, painful swallowing, white plaque on the tonsils and
redness of the throat and tonsils.



"The importance in differentiating patients with tonsillitis from those
with glandular fever [mononucleosis] is the prevention of spontaneous
rupture of the spleen and acute intra-abdominal hemorrhage," potential
complications of mononucleosis, the authors write. Currently,
distinguishing between them requires an expensive mononucleosis spot
test.



Dennis M. Wolf, B.Sc., DO-HNS, MRCS, and colleagues at St. George's
Hospital, London, retrospectively analyzed laboratory tests from 120
patients with infectious mononucleosis and 100 patients with bacterial
tonsillitis treated at their facility. All patients were given the spot
test for mononucleosis and additional blood tests were performed to
determine the number of lymphocytes (a particular type of white blood
cell involved in the body's immune response) and overall white blood
cell count.



Total white blood cell count was significantly increased in the
tonsillitis group compared with the mononucleosis group (16,560 cells
per mcL vs. 11,400 cells per mcL), but the lymphocyte count was higher
in the mononucleosis group (6,490 cells per mcL vs. 1,590 cells per
mcL). The ratio of lymphocyte/white blood cell count ratio averaged.54
in the mononucleosis group and.10 in the tonsillitis group.



Based on this data, the researchers determined that a ratio higher
than.35 would have a sensitivity of 90 percent and a specificity of 100
percent for the detection of mononucleosis, meaning that an individual
with a ratio this high would be correctly diagnosed with mononucleosis
90 percent of the time and an individual with a ratio of.35 or lower
would be correctly diagnosed as not having mononucleosis 100 percent of
the time. "The specificity and sensitivity of this test seem to be
better than the mononucleosis spot test itself," the authors write.



"In conclusion, we recommend that the
lymphocyte–white blood cell count ratio should be used as an indicator
to decide whether mononucleosis spot tests are required," they
continue. "Results from our retrospective pilot study suggest that the
lymphocyte–white blood cell count ratio could be a quickly available
alternative test for the detection of glandular fever [mononucleosis]."



Please see the article for additional information, including other
authors, author contributions and affiliations, financial disclosures,
funding and support, etc.



Arch Otolaryngol Head Neck Surg. 2007;133:61-64.