How are antistreptococcal antibodies interpreted?
“Normal” ranges for these antibody titers depend on the patient’s age, geographical location, epidemiologic circumstances, and the time of the year. In the United States, an ASO titer is considered elevated at 240 Todd units in adults and 320 Todd units in children. ADB titers of >120 Todd units in adults and >240 Todd units in children are also typically considered to be elevated. Samples should be drawn at 2 to 4-week intervals and processed simultaneously. Antibody levels peak at 4 to 5 weeks after the pharyngeal infection (with ADB peaking latest). Using ASO in conjunction with an additional serological test produces a sensitivity approaching 90+%.
