[Determination of serum digoxin: a path to better control of therapy?].

The usefulness of serum digoxin measurements in the diagnosis of digitalis toxicity was studied prospectively in hospitalized patients. Serum levels were increased above 2 ng/ml in 28 of 32 cases with digoxin-induced arrhythmias and/or gastrointestinal symptoms, whereas only 1 of 35 non-toxic patients had an abnormal serum concentration. There was, however, no direct relationship between the type of toxic manifestation and absolute values of serum digoxin.