All the following are done in the initial assessment of digoxin toxicity EXCEPT

(B). The serum digoxin level should be assessed at least 6 hr after ingestion and carefully interpreted in the setting of clinical symptoms because the digoxin level alone does not entirely reflect the severity of intoxication. In acute ingestions, serum potassium is an independent marker of morbidity and mortality, with levels >5.5 mEq/L predicting poor outcomes. In chronic toxicity, serum potassium is less useful as a prognostic marker and may be altered due to concomitant use of diuretics.