title: The diagnostic value of determination of intraerythrocytic sodium and potassium concentrations versus plasma digoxin concentration in digoxin intoxication.
abstract: Plasma digoxin measurements have proved unserviceable as a means of differentiating between toxic and non-toxic patients. In order to assess the value of a biological effect of digoxin in this discrimination, intraerythrocytic sodium and potassium concentrations were determined in 55 chronically digitalized patients of whom 10 were digoxin-intoxicated according to ECG criteria. Digitoxicity was associated with elevated intraerythrocytic sodium concentration (mean +/- SEM 19.3 +/- 1.2 versus 11.3 +/- 0.3 mmol/l, p less than 0.001) and reduced intraerythrocytic potassium concentration (94.6 +/- 2.3 versus 100.0 +/- 0.6 mmol/l, p less than 0.001) compared to non-toxic patients. Mean (+/- SEM) plasma digoxin concentrations in the two groups were 3.14 +/- 0.41 and 1.57 +/- 0.09 nmol/l, respectively (p less than 0.001). When diagnosing toxicity in chronically digitalized patients, plasma digoxin and intraerythrocytic sodium determinations showed sensitivities of 60 and 100%, respectively. The predictive values of a positive test were 75% for plasma digoxin and 83% for intraerythrocytic sodium.
mesh_terms: D000368:Aged; D004077:Digoxin / Q000008:administration & dosage / Q000097:blood* / Q000506:poisoning; D004912:Erythrocytes / Q000032:analysis*; D006801:Humans; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000097:blood*
chemical_list: D004077:Digoxin; D012964:Sodium; D011188:Potassium