title: [A simplified radioimmunoassay for digoxin determination using a 125-j-labelled, solid-phase kit (author's transl)].
abstract: Our experience with a commercially available kit (Radioimmunoassay DIGOXIN, Boehringer, Mannheim) using (125J)-labelled digoxin and antibody-coated tubes is reported. This simplified method requires only two pepetting steps per sample and results can be obtained in 70 min. The intra- and interassay coefficient of variation ranged between 7% and 8%. The specific digoxin antibody gave no clinical relevant cross-reactions with spironolactone or prednisone (less than 0.0007%). Of the digoxin metabolites the aglucone digoxigenin showed 31% cross-reaction while the more important cardioactive metabolites digoxigenin-bis- and mono-digitoxide had the same binding affinity to the antibody as digoxin, beta-methyldigoxin and beta-acetyldigoxin. Cross-reaction with digitoxin was 6.8%. More than double-fold dilution of serum protein concentration showed little influence on the digoxin values measured. The results obtained by this new kit compare closely with those obtained by our tritium-labelled kit (r = 0.94, p less than 0.001). Therefore, the upper therapeutic limit of 1.9 ng/ml can be adopted for this method.
mesh_terms: D000906:Antibodies; D003429:Cross Reactions; D004077:Digoxin / Q000097:blood*; D006801:Humans; D011863:Radioimmunoassay / Q000379:methods*; D011933:Reagent Kits, Diagnostic
chemical_list: D000906:Antibodies; D011933:Reagent Kits, Diagnostic; D004077:Digoxin
vernacular_title: Vereinfachte Serum-Digoxin-Bestimmung mit einem Jod-125-Solid-Phase-Test.