Widely differing plasma digoxin values in patients with congestive heart failure and severe liver dysfunction. A method-dependent problem.

We studied plasma digoxin levels by three methods in patients with congestive heart failure who had no, mild to moderate, and severe liver dysfunction secondary to the heart failure. Our results indicate that in patients with severe liver dysfunction, marked discrepancies in plasma can occur, depending on the methodology employed. The discrepancy is likely due to the presence of a digoxinlike immunoreactive substance.