Alternative Names Lanoxin test, digitalis test, serum digoxin
Definition This test measures the amount of digoxin in the blood. Digoxin is a drug used to treat congestive heart failure and certain types of arrhythmias, or irregular heart beats. Digoxin is a medication that needs to be monitored closely, since the amount prescribed is often close to the level at which the drug can be toxic.
Who is a candidate for the test? This test is done on persons who are taking digoxin to determine if the dose of medication being taken is correct.
How is the test performed? To obtain accurate results, the timing of the test is very important. If someone is just started on digoxin, it is important to wait 6-8 hours after a dose of the medication has been swallowed to obtain a blood sample. If someone has been on digoxin treatment for a long time it is important to try to obtain a blood sample just before a dose of the medication is taken.
In order to measure the amount of digoxin in the blood, a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube called a tourniquet is wrapped around the upper arm to enlarge the veins in the lower arm by restricting blood flow through them. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle, and is collected in a syringe or vial for testing in the laboratory. After the needle is withdrawn, the puncture site is covered with a bandage for a short time to prevent bleeding.
What is involved in preparation for the test? A doctor can provide specific instructions.
What do the test results mean? Normal values for digoxin in the blood range from 0.5-2.0 ng/ml (nanograms per millilitre). Abnormal values for digoxin in the blood may mean the medication dose is too high or too low. However, some drugs, such as spironolactone, may interfere with the test results. In addition, people with liver, renal failure or pregnant women and newborns may carry substances in their bodies that may alter the results of the test. If digoxin levels are too high, the body could become poisoned. Serious side effects can occur such as nausea, vomiting, mental status changes, irregular heartbeat and vision changes.
Author: Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
