ANTI-N-FORM ANTIBODY IN HEMODIALYSIS-PATIENTS

The anti-N-form antibody is produced by dialysis patients following re use of dialyzers sterilized with formaldehyde and it has been implicat ed as a cause of hemolytic anemia. Formaldehyde is one of the common d isinfectants used for reprocessing capillary hemodialyzers, The safety of formaldehyde and the clinical significance of anti-N-form antibody need further evaluation. Amongst 45 patients practising dialyzer reus e, anti-N-form antibody was detected in 5 (11.1%), but not amongst 111 patients not reusing their dialyzer (p < 0.005). The presence of anti -N-form was not related to the sex, or duration of dialysis with and w ithout dialyzer reuse. There was no overt hemolysis in the patients wi th positive anti-N-form antibody. Direct Coombs' test was positive amo ngst 80% of all tested patients with anti-N-form antibody, and in 38% of patients reusing dialyzers but without anti-N-form antibody. No tes ts of hemolysis (including direct Coombs' test) discriminated between anti-N-form antibody-positive and -negative patients, nor between anti -N-form antibody patients with and without overt hemolysis. The best d iagnostic test for hemolysis in anti-N-form antibody-positive patients was hematocrit rise after cessation of dialyzer reuse. It appears tha t despite the induction of anti-N-form antibody, hemolysis is rarely a serious consequence of dialyzer reuse.