title: Digoxin assay anomalies due to digoxin-specific Fab immunotherapy.
abstract: We demonstrate that digoxin-specific Fab antibody fragments, used in the treatment of severe digitalis intoxication, cause a marked interference with both fluorescence excitation transfer immunoassays and radioimmunoassays for digoxin. In addition, we describe a rapid ultrafiltration method that avoids the Fab-induced interference and affords excellent accuracy and precision. This technique will provide a useful adjunct to the clinical evaluation of patients with digoxin toxicity who are recipients of antidigoxin immunotherapy by enabling a precise determination of their serum digoxin concentrations. By separating the free and protein-bound digoxin this technique also may be useful in evaluating serum digoxin concentrations in patients with abnormal plasma protein concentrations.
authors.affiliation: Division of Medical Genetics, Eunice Kennedy Shriver Center for Mental Retardation, Waltham, MA 02254.
authors.forename: M
authors.initials: M
authors.lastname: Natowicz
authors.forename: L
authors.initials: L
authors.lastname: Shaw
mesh_terms: D000368:Aged; D004077:Digoxin / Q000097:blood* / Q000276:immunology / Q000506:poisoning; D005260:Female; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000032:analysis* / Q000627:therapeutic use; D007167:Immunotherapy; D008297:Male; D011041:Poisoning / Q000628:therapy; D011863:Radioimmunoassay; D014462:Ultrafiltration
chemical_list: D007140:Immunoglobulin Fab Fragments; C050199:digoxin antibodies Fab fragments; D004077:Digoxin