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A titer is a measurement of the amount or concentration of a substance in a solution. It usually refers to the amount of antibodies found in a person's blood.


Blood titer measurements can help determine medical treatment. Antibody titers show if a person is immune to diseases such as measles, chickenpox, or hepatitis. They can also help measure harmful antibodies related to lupus.

A titer measurement is expressed as a ratio, such as 1:40.


Ashihara Y, Kasahara Y, Nakamura RM. Immunoassays and immunochemistry. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 44.

Review Date 8/14/2015
