Digoxin Level
Also written as: Serum digoxin, Digoxin concentration
The amount of the heart medication digoxin in blood, where the timing of the draw matters a lot.
What it measures
The concentration of digoxin, a heart rhythm and heart failure medication, in the blood. Digoxin moves slowly from blood into tissue after each dose, so samples drawn within about six hours of a dose read misleadingly high; the standard draw is at least six to eight hours after the last dose, often just before the next one.
Why a doctor orders it
Levels are checked when the drug is started, after dose changes, when kidney function changes, when an interacting medication is added, or when the clinical picture raises the question of a level that has drifted. Digoxin is cleared by the kidneys and has one of the narrowest safety windows of any common medication.
What is generally associated with a higher result
Higher levels are broadly associated with declining kidney function, dehydration, interacting medications - amiodarone, verapamil, and certain antibiotics are classic examples - and samples drawn too soon after a dose, before the drug has finished distributing into tissue. The target range is individual and set by the prescriber.
What is generally associated with a lower result
Lower levels are broadly associated with missed doses, interacting drugs and supplements that reduce absorption or speed clearance, including St. John's wort, and differences in how the drug is absorbed.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- Timing - draws within about six hours of a dose read falsely high
- Kidney function and hydration
- Several common interacting prescriptions, plus St. John's wort
- Electrolyte levels, which are usually checked alongside the drug level
Questions to take to your appointment
- How long after my last dose was this drawn?
- Have any of my other prescriptions changed since the last level was checked?
- Are my potassium, magnesium, and kidney function being monitored with this?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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