Exposure history is critical to diagnosis. In psittacosis patients, complete blood count shows leukopenia, thrombocytopenia, and moderately elevated liver enzymes.

• Leukocytosis
• Increased ESR
• Increased CRP
• Elevated Liver enzymes
• Rise in creatinine kinase
• Hyponatremia may be noticed
• Rise in blood urea nitrogen levels
• Urinalysis may show proteinuria

• Culture of C. psittaci is demanding and requires a level 3 laboratory isolation facility because of the risk of laboratory transmission, so it is rarely performed.
• Microbiological cultures from respiratory secretions.
• Culture of Chlamydia psittaci is hazardous and should only be carried out in biosafety laboratories.
• It is a tedious process and seldom done.

Serology is the principal method of confirming the diagnosis of C. psittaci. There are two types of serologic tests available:

• Microimmunofluorescent antibody test (MIF): The MIF test is the most sensitive and specific serologic test for C. psittaci but is only available in special laboratories.

• Complement fixation (CF): It is the most widely available test but cannot differentiate among the chlamydial species.

• PCR techniques have been utilized in outbreaks for several years and can give a rapid, specific diagnosis, which is particularly important in severe infection.

• More research is needed to support the efficacy and sensitivity of monoclonal antibody tests.