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Digoxin Drug Level

Does this test have other names?

Therapeutic digoxin monitoring, dig level

What is this test?

This test measures the amount of the heart drug digoxin in your blood.

Digoxin is a drug that helps your heart pump more efficiently when you have an irregular heartbeat or congestive heart failure (CHF). It may also be given to control heart rate for certain irregular heart rhythms.

When you take digoxin, it's important that the drug be at the right level for you to benefit from it. Your doctor may need to adjust your dose if your levels are too high or too low in dosing.

Why do I need this test?

You may need this test to have your digoxin level checked when you first start treatment to make sure you are taking the right dose. The dose level that works best for most people may be called the therapeutic range. A digoxin dose is not the same for everyone, so your health care provider may need to adjust your dose over time.

You may need this test to:

  • Determine your therapeutic dose of digoxin after you begin taking the drug

  • Periodically monitor the drug level to make sure you continue to get a therapeutic dose

  • See whether certain symptoms you are experiencing may be related to your digoxin level

What other tests might I have along with this test?

Your doctor may also order other tests if you have signs or symptoms that suggest your digoxin level is too high or too low. These tests include an electrocardiogram, or ECG. Your doctor may also order tests to check your kidney health if you have kidney problems. He or she may also order tests to check your blood potassium and magnesium levels. Kidney problems and low levels of potassium or magnesium in the blood may lead to digoxin overdose.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Results are given in nanograms per milliliter (ng/mL).

If you are taking digoxin because of an irregular heartbeat, your ideal range may be between 1.5 and 2.5 ng/mL. But this range is widely variable, because this test is more commonly used to check for toxicity when treating an irregular heart beat instead of to find out how well the drug is working as a treatment.

If you have congestive heart failure, the ideal range may be between 0.5 and 0.8 ng/mL. When used for CHF, the target range for this test is important to find out both how well the drug is working as treatment and to avoid the risk for toxicity.

If your digoxin level is outside the therapeutic range, your doctor may raise or lower your digoxin dose.

If you have CHF and your digoxin levels are below the normal treatment range, you may develop symptoms of persistent heart failure:

  • Fluid buildup in your lungs or your legs

  • Shortness of breath

  • Changes in your heartbeat

  • Fatigue

Digoxin levels above the normal treatment level may cause:

  • Nausea or vomiting

  • Dizziness

  • Changes in your heartbeat

  • Confusion

  • Blurred or yellow-tinted vision

Very high levels of digoxin can cause a condition called digoxin toxicity. This may require treatment with a medication to block the effects of the drug. Digoxin side effects can occur even when levels are considered to be within normal limits, so it's important to report any new symptoms to your doctor.

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Taking digoxin within six to 12 hours before this test can affect your results.

Many other medications can also affect your digoxin level, including antacids, drugs that lower cholesterol, over-the-counter medications for diarrhea, bulk laxatives, and nutritional supplements. Foods high in fiber can also affect your results.

How do I get ready for this test?

Ask your doctor when you should stop taking digoxin before the test. In addition, make sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.