[Serum concentration of digitalis glycosides as a therapeutic guide]

The concentration of digitalis glycosides in serum may serve as a useful guide in adjusting digitalis glycoside dosage to individual needs. Radio-immunological determination of digoxin is mainly indicated when patients with renal failure, hypothyroidism or hyperthyroidism or elderly subjects are treated with digoxin, when signs of digitalis intoxication are present or when patient compliance has to be assessed. However, factors which alter myocardial sensitivity to digitalis glycosides must be considered in the interpretation of serum concentrations of digitalis glycosides.