Tested pos for syphilis in 2016. titer was 1:64. later titer were 1:32, 1:32, 132, 1:128 (lab made error bc 3 days later was 1:32 @ to retest. then 4 years later it was 1:4, & recent is 1:16. could 1:4 be error? im hiv+ also. have 0 symptoms?

A four fold difference in titer could be explained by the expected variations in test performance. You ought to be under the care of a doctor for treatment of HIV infection and s/he should be able to address your syphilis status also. Wish you good health!

Presumably you were treated? What stage of syphilis and how treated? Decline to 1:4 suggests good response to treatment, but later rise of titer to 1:16 suggests possible reinfection or reactivation of previous infection. See a doctor, ideally infectious diseases or STD specialist. You may need spinal tap to check for neurosyphilis, the most common reason for reactivation after Rx. Good luck.