SERUM DIGOXIN CONCENTRATION - INCREASE AFTER REST IN DIFFERENT BODY POSITIONS

If outpatients are allowed to rest in the supine position before their blood is sampled, serum digoxin increases. In a recent study, the serum digoxin concentration after 2-h standardized supine rest correlated better with the clinical status of patients than the value before rest. In the present study, 21 outpatients were studied on 2 consecutive days, ≤24 h after the latest dose of digoxin. Blood samples for the assay of serum digoxin were taken on arrival at the department and after 1.5- and 2-h rest either supine or sitting (random order). The increases after 1.5-h rest were 12% (0-25%; p < 0.001) and 12% (-3-47%; p < 0.001), supine and sitting, respectively. The respective increases after 2-h rest were 14% (-11-32%; p < 0.001) and 16% (0-74%; p < 0.001). There were no statistically significant differences between the increases in serum digoxin concentration after supine and sitting rest. These results make it possible to recommend standardized rest in the sitting position (1.5-2 h) for outpatients before blood samples are collected when reliable serum digoxin analyses are of importance. © 1990 Raven Press, Ltd., New York.