What is being tested?
Digoxin is a drug used to treat heart failure and abnormal heart rhythms. This test measures the amount of digoxin in the blood. Heart failure, including congestive heart failure (CHF), causes the heart to become less effective at circulating blood. As a result, blood backs up into the legs, hands, feet, lungs and liver, causing swelling, shortness of breath, and fatigue.

Digoxin is prescribed to alleviate some symptoms of heart failure. It strengthens the contractions of the heart and helps it to pump blood more efficiently. Digoxin also helps control the heart rate and abnormal heart rhythms known as arrhythmias. It will not cure heart failure or arrhythmias, which are chronic conditions, but can help to manage the symptoms along with diet, exercise, and other medications.

Digoxin levels need to be monitored because digoxin is a drug that has a narrow safety range. If the level in the blood is too low, symptoms may recur. If the level is too high, toxicity may occur with possible side effects such as:

dizziness;

blurred vision or seeing yellow or green halos;

vomiting;

diarrhea;

irregular heartbeat; or

difficulty breathing.

Digoxin dosage may be adjusted based on levels measured.

How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?
No special preparation is needed, but timing of the sample for testing is important. When having your blood drawn, tell the laboratorian when you took your last dose of digoxin. You may want to write down the exact time at which you took your dose and when the blood was drawn. This information will be useful if your doctor has any questions about your levels.