[Serum dixogin determination. Clinical significance, results and error consideration based on comparative studies...

In order to compare 5 different radioimmunoassays (RIA's) and their results we determined the digoxin concentration in the serum of 186 patients and point out some sources of error. We consider the following points important: 1. There were found varying results in the determination of digoxin concentration in patient's sera using different RIA's. 2. One of the essential reasons for these differences are discrepancies of the RIA standards which belong to each kit. 3. It should be required that the control standard is equal to all RIA's. 4. Each laboratory which carries out digoxin determinations should, in collaboration with the clinic, work out and announce its own guide-line values for the RIA used in regard to the optimal therapeutic range and also to overdoses.