After giving treatment for Syphilis, the response to treatment can be best assessed by –
FTA–ABS
VDRL
TPHA
Immobilization test
Specific treponemal tests (FTA-ABS, TPHA, TPI) are of little value as indicators of clinical cure, as they tend to remain positive in spite of Treatment.
Non treponemal tests (eg VDRL) will become nonreactive or will be reactive at lower titers after therapy, so can be used for monitoring patient's response to treatment. These tests usually become negative 6-18 months after effective treatment of syphilis.