Digoxin

Digoxin is a heart medicine used to help control certain irregular heart rhythms and to ease symptoms in some people with heart failure. This blood test measures how much digoxin is in your bloodstream, showing how your body is absorbing and clearing the drug at the time of sampling.

Levels vary with dose timing, kidney function, and how the drug moves from blood into tissues. For that reason, the sample is usually collected at a consistent point in your treatment and after the medication has had time to distribute, so the result reflects your typical level. Your clinician may order this test along with kidney and electrolyte tests.

Digoxin has a narrow safety window, which means the difference between an effective dose and a harmful dose is small. Too little may not control your condition, while too much can cause side effects affecting the heart, stomach, vision, and nervous system. Checking your level helps your clinician tailor the dose, identify drug interactions, and reduce the risk of toxicity.

This test is often ordered when starting therapy, after a dose change, when adding or stopping other medicines, if kidney function changes, in older adults, or when you have symptoms that could be related to digoxin effect such as nausea, decreased appetite, confusion, vision changes, or an irregular heartbeat.

Your result is interpreted together with the time of your last dose, your symptoms, your heart rhythm, kidney function, and electrolyte levels. A value that looks higher or lower than expected can often be explained by sample timing or recent dosing changes, so your care team will consider the full picture.

If the level suggests excessive exposure and you have symptoms, your clinician may adjust or temporarily hold doses, review other medicines for interactions, obtain an electrocardiogram, and repeat labs. If it appears lower than intended, the plan may include adjusting the dose or timing, addressing interactions, and rechecking the level. Do not change or stop digoxin without medical advice.

Some situations can make results less reliable, such as soon after receiving digoxin immune antibody fragments for overdose or the presence of substances that cross react in certain assays. Tell your clinician about recent treatments, supplements, and pregnancy so they can interpret the result correctly.