In cases of infectious mononucleosis, what test is typically positive?

In cases of infectious mononucleosis, the heterophile antibody test is typically positive. This test, often referred to as the Monospot test, is specifically designed to detect heterophile antibodies that are produced in response to the Epstein-Barr virus (EBV), the primary cause of infectious mononucleosis. These antibodies develop within the first few weeks of infection and can usually be detected within a short timeframe, making the heterophile antibody test an effective diagnostic tool for identifying this condition.

While the complete blood count can provide supportive information, such as an elevated white blood cell count or atypical lymphocytes, it is not specific enough to confirm infectious mononucleosis on its own. The strep throat test is focused on streptococcal infections and does not relate to mononucleosis. Liver function tests may reveal elevated liver enzymes in some cases of infectious mononucleosis, but they are not definitive for diagnosing the condition. Thus, the heterophile antibody test stands out as the most reliable and direct means of confirming infectious mononucleosis.