Serum or plasma concentration of **digoxin** (digitalis glycoside)

Why This Test Is Done

Your doctor may order a digoxin test if you’re taking digoxin (brand names like Lanoxin) to treat conditions like heart failure, atrial fibrillation, or irregular heartbeats. It’s also used to monitor levels in people with kidney problems, as these organs help clear the drug from your body. Sometimes, it’s checked before surgery or if you experience symptoms like nausea, vomiting, or vision changes that might signal too much or too little of the medication.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for a few hours before the blood draw if your test involves serum. Bring a list of all medications, including over-the-counter drugs and supplements, to share with your healthcare provider. Avoid smoking or drinking coffee for 30 minutes before the test if instructed.

What Happens During the Test

A healthcare professional will insert a small needle into a vein in your arm to draw blood. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis. The test typically takes a few minutes, and you can return to your normal activities afterward.

What the Results Mean

Results are usually reported as a concentration in nanograms per milliliter (ng/mL). Too much digoxin can cause symptoms like dizziness, headaches, or irregular heartbeat, while too little may not provide enough heart support. Your doctor will interpret the results in relation to your symptoms, other medications, and kidney function.