Three-years' experience in interlaboratory testing of commercial digoxin kits.

Results of digoxin assays obtained from participants in Survey Programs of the College of American Pathologists over a span of three years are reviewed according to recovery rates and clinical interpretation of results obtained. Discrepancies in recovery rates by kits employing iodinated and tritiated antigens were observed in 1972 and 1973. More uniform recovery rates were observed in 1974. Clinical interpretation of the results obtained by participating laboratories was affected by the methods used during the first two years and by the apparent failure of individual laboratories to establish their own therapeutic ranges.