[Clinical experiences with the serum digitalis concentration. 1006 radioimmunological determinations].

Serum digitalis concentration was measured radioimmunologically on 1006 patients in the period from 1974-1976. The serum levels were correlated with the clinical signs of digitalis toxicity and the indications for determination of the serum digoxin concentration were established. Clinical signs of toxicity appear at a serum level of digoxin above 2.5 ng/ml. Therapeutic limits (range) are most influenced by individual factors. Serum digoxin determination is especially necessary in patients with renal failure and in undisciplined patients with erratic digitalis intake. It is a useful aid in controlling the course of digitalis intoxication, in "low dosage" digitalization and in the case of possible drug interactions.