Faster and Easier Radioimmunoassay of Digoxin

[摘要] We describe an improved radioimmunoassay method for serum digoxin, with 125I as tracer, to eliminate the problems that endanger the validity of this assay: apparent instability of tracer, time-dependence of charcoal separation of free and bound fractions, and influence of sample-to-sample differences on results. Principal innovations leading to a more rugged and reliable test are the use of ( a ) a stable [125I] tyros ine-methyl-ester of digoxin, ( b ) ammonium sulfate to separate bound and free fractions, ( c ) a fresh serum pool for the standard curve, and ( d ) individual specimen blanks. Results compare favorably with those of the properly-controlled, original tritium method of Smith et al. [ New Engi. J. Med. 281, 1212 (1969)] in terms of digoxin values, while the method excels it in convenience and speed. Between-run precision is 11% (CV) over the range of interest (mean, 2.7 µg/liter), sensitivity is 0.2 µg/liter, and recovery of added digoxin averages 102%.

[学科分类] 过敏症与临床免疫学