[Determination of serum digoxin. A comparison between RIA and EIA (author's transl)]

The results of two radioimmunoassays (RIA, precipitating technique), of a homogenous (EMIT) and a heterogenous (ELISA) enzyme immunoassay (EIA) for ascertaining the amounts of digoxin showed a good correlation in precision and a reasonably satisfying correlation in the recovery. However, there was a clear discrepancy in the amounts of digoxin concentrate in the serum of patients. Only the RIA of Abbott and the EIA of Boehringer showed no significant differences. Particularly noticeable was the tendency towards lower values in the EMIT-technique as well as its liability to unspecific serum changes (lipaemia etc.), which often made the detection of digoxin impossible. The routine use of this technique appears problematic. The need for establishing one's own laboratory and test-specific therapeutical range is pointed out.