A patient with findings strongly suggestive of secondary syphilis has a reactive treponemal test but a nonreactive undiluted RPR. What should the laboratory do to evaluate a possible prozone effect?
1Repeat the nontreponemal test using serially diluted serum✓ 정답
2Report syphilis excluded because the undiluted RPR is nonreactive
3Heat-inactivate the serum and repeat only the treponemal test
4Replace serum with EDTA whole blood in the RPR
해설
Antibody excess can prevent visible lattice formation and cause a false-negative undiluted nontreponemal test. Testing serial dilutions can remove the prozone and reveal reactivity.