When measuring antibody titers, a lower titer indicates less antibody is present. True or false?

• A. True
• B. False
• C. Not determinable
• D. Sometimes

Answer: (A)

The amount of antibody in a sample is reflected by the titer, which is defined as the highest dilution at which antibodies are still detectable. Because you can dilute more when there is more antibody present, a higher titer indicates more antibody. Therefore, a lower titer means there is less antibody present. For example, if a sample tests positive up to a 1:80 dilution but not at 1:160, the titer is 80; another sample positive up to 1:1280 has more antibody and a higher titer. The statement is true.