Fasting Required: No Specimen: Serum Results: 1-2 Business days Description: The mono test is used to help determine whether a person with symptoms has infectious mononucleosis (mono). It is frequently ordered along with a complete blood count (CBC). The CBC is used to determine whether the number of white blood cells (WBCs) is elevated and whether a large number of responsive cells are present. Mono is categorized by the presence of abnormal white blood cells.