Measurement of Digoxin in Plasma and its use in Diagnosis of Digoxin Intoxication

A method for measuring the plasma-digoxin concentration uses the measurement of its inhibitory effect on (86)Rb uptake by human red cells in vitro. Patients receiving digoxin in whom there was no clinical evidence of digoxin intoxication had plasma digoxin concentrations ranging from 0.8 to 4.5 mmug./ml. Patients presenting with convincing clinical evidence of digoxin intoxication had plasma digoxin concentrations ranging from 4 to greater than 8 mmug./ml. It is suggested that the plasma digoxin concentration may be used as an aid in the diagnosis of digoxin intoxication.