Regarding false positive Digoxin level
Many common clinical conditions may lead to false positive elevations of plasma digoxin and erroneous medical management. Actually, many experts don't believe in checking digoxin level unless there is any clinical manifestation due to many artifactual factors such as poor assay quality, incorrect timing or technique of drawing blood samples. Atleast, in following 3 conditions, there is an increase of endogenous digoxin-like substances in plasma which may lead to false positive result with total error upto 0.6 - 1.8 ng/mL.
- chronic renal failure
- hepatobiliary disease
- in the third trimester of pregnancy
Also atleast 3 commonly used drugs (like steroid derivative drugs) may cross react with the digoxin radioimmunoassay and give false postive values.
- spironolactone
- methylprednisolone
- Tobramycin
Note: New born neonates can have very high false postive digoxin level upto 4 ng/mL due to increased levels of endogenous digoxin-like substances.
1. Digoxin-like substance in the serum of uremic patients before and after hemodialysis - Cardiovascular Drugs and Therapy, Volume 2, Number 6 / January, 1989
2. Cross-Reactivity of TDX and OPUS Immunoassay Systems for Serum Digoxin Determination. Therapeutic Drug Monitoring. 19(6):657-662, December 1997.
3. Falsely elevated digoxin levels: another look - Ther Drug Monit. 1989 Sep;11(5):572-3
