Serum Glycoside Levels by Rubidium Assay

Abstract

Serum glycoside concentrations were measured by rubidium 86 assay in 88 patients on maintenance digitalis therapy not manifesting digitalis toxicity and in 39 patients manifesting digitalis toxicity by cardiac arrhythmias. The nontoxic range and median in nanograms per milliliter were 0 to 5 (1.2) for digoxin, 0 to 38 (20.5) for digitoxin, and 2 to 40 (23) for digitalis leaf. Toxic levels (digoxin, 2 to 44 [5.5]; digitoxin, 15 to 56 [37]; digitalis leaf, 31 to 64 [38]) were significantly higher (P