title: Determination of myocardial and serum digoxin concentrations in children by specific and nonspecific assay methods.
abstract: After obtaining samples at open heart surgery, serum and right atrial digoxin concentrations were measured in 25 children by a nonspecific, direct radioimmunoassay method (NS) and by a specific method in which digoxin was separated from its metabolites by HPLC before radioimmunoassay was applied to the digoxin fraction (S). Digoxin was detectable by S assay (sensitivity 0.1 ng/g) in 16 heart specimens and 22 serum samples. The mean and range of the S/NS ratio was 0.74 (0.23 to 2.63) for serum and 0.81 (0.068 to 1.38) for atrial tissue. By NS assay the mean and range of the atrial/serum ratio was 78.1 (2.4 to 340, n = 21) and by S assay the corresponding values were 100 (10.7 to 318, n = 15). A multiple linear regression indicated that 72.5% of the variance of the heart digoxin concentrations measured by S assay were accounted for by the variables height, body weight, daily digoxin dose before operation, plasma digoxin concentration by S assay, and BUN.
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001806:Blood Urea Nitrogen; D001827:Body Height; D001835:Body Weight; D006348:Cardiac Surgical Procedures; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D004077:Digoxin / Q000008:administration & dosage / Q000032:analysis* / Q000097:blood; D005260:Female; D006325:Heart Atria / Q000032:analysis; D006801:Humans; D007223:Infant; D008297:Male; D009206:Myocardium / Q000032:analysis*; D011292:Premedication; D011863:Radioimmunoassay
chemical_list: D004077:Digoxin