Digoxin Intoxication: the Relationship of Clinical Presentation to Serum Digoxin Concentration

concentration has been used to study the interrelation-ships of circulating levels of the drug and various factors in the clinical setting in 48 hospitalized patients with cardiac rhythm disturbances due to digoxin intoxication. 131 patients on maintenance doses of digoxin without toxicity and 48 patients with equivocal evidence of digoxin excess were also studied and compared with the toxic group. Patients with cardiac rhythm disturbances due to di-goxin intoxication tended to be older and to have di-minished renal function compared with the nontoxic group; body weight, serum potassium concentration, underlying cardiac rhythm, and nature of cardiac disease were not significantly different for the groups as a whole. Despite comparable mean daily digoxin dosages, digoxin intoxicated patients had a mean serum digoxin concen-tration of 3.7 ±1.0 (SD) ng/ml, while nontoxic patients had a mean level of 1.4 ±0.7 ng/ml (P < 0.001). 90% of patients without evidence of toxicity had serum di-goxin concentrations of 2.0 ng/ml or less, while 87 % of the toxic group had levels above 2.0; the range of over-lap between the two groups extended from 1.6 to 3.0 ng/ ml. Patients with atrioventricular block as their prin-cipal toxic manifestation had a significantly lower mean serum digoxin concentration than those in whom ec-topic impulse formation was the chief rhythm disturb-ance. Patients with equivocal evidence of digoxin excess had received comparable daily maintenance doses of digoxin but had a mean serum concentration of 1.9 +0.8 ng/ml, intermediate between those of the nontoxic (P < 0.005) and toxic (P < 0.001) groups. Renal function as judged by mean blood urea nitrogen concentration was also intermediate