About the Test
Purpose of the test
A lithium test is used to evaluate the concentration of the drug in the blood. Knowing how much is in the blood is important for diagnosing lithium poisoning and monitoring your health if you take lithium as a medical treatment for bipolar disorder and other mental health conditions.
A lithium test can confirm if you have lithium poisoning, also known as lithium toxicity. The test can also determine the severity of lithium poisoning.
Lithium testing can also be used to monitor health changes over time and see how you respond to treatment. If you’re receiving treatment with lithium, doctors may check your levels to establish a proper dose of the drug.
A type of drug called a mood stabilizer, lithium is most often used to prevent and treat episodes of mania in patients with bipolar disorder. Lithium is sometimes prescribed to manage the symptoms of other mental health conditions.
Lithium has a narrow therapeutic window. This means that small differences in the dose or blood concentration of lithium can impact how well the drug works and whether or not it is safe.
Treatment is not effective if lithium levels are below the therapeutic range. But if lithium levels are too high, you may experience lithium toxicity, which can cause serious health complications.
As a result, lithium treatment requires careful therapeutic drug monitoring. Doctors check lithium levels frequently at the start of treatment to determine a dosage that causes levels to be in a therapeutic range. Lithium levels are then measured again every few months or before a change in drug dosage.
What does the test measure?
A lithium test measures the concentration of the drug in a sample of blood. Measurements are reported in millimoles per liter (mmol/L).
As a medication, lithium is usually taken by mouth. It is absorbed by the gastrointestinal system and enters the blood, allowing the blood concentration to be measured.
Lithium levels in the blood must be within a certain range to effectively manage symptoms of bipolar disorder and other mental health conditions. This is called a therapeutic range or therapeutic window.
When should I get a lithium test?
You may be prescribed a lithium test if your doctor is recommending treatment with lithium for a condition such as bipolar disorder.
Lithium tests are ordered at the start of treatment to set up a dose of the medication that maintains a lithium blood level within the therapeutic range.
After your doctor determines that the dose of lithium is appropriate, they may order periodic tests to ensure that your lithium level remains within that therapeutic range.
You may have a lithium test if you experience significant mood changes or if you continue to have symptoms of bipolar disorder. The results of lithium tests can help your doctor make any necessary adjustments to your treatment.
You may also be prescribed a lithium test if you have signs of lithium poisoning, which can occur if too much lithium is taken at once or if lithium builds up in the blood over time. Possible signs of lithium poisoning include:
- Nausea and vomiting
- Stomach pain or diarrhea
- Weakness
- Dizziness
- Slurred speech
- Loss of muscle control
- Impaired thinking or memory
If you have been prescribed the drug, you can talk with your doctor about ongoing lithium testing including a plan for monitoring your levels and the signs of lithium toxicity to look out for.
Finding a Lithium Test
How can I get a Lithium test?
A lithium test is typically ordered by a health care provider. Lithium treatment is usually prescribed by a psychiatrist, a medical doctor who specializes in treating mental health conditions. Lithium levels may initially be monitored by your psychiatrist.
Once you are on a stable dose of lithium, monitoring may be done by other members of your health care team, such as your primary care provider or a mental health nurse.
Testing usually requires a visit to a doctor’s office, laboratory, or hospital where a blood sample is collected.
Can I take the test at home?
There are no at-home test kits currently available to evaluate lithium levels in the blood.
How much does the test cost?
The cost of lithium testing depends on a number of factors, such as health insurance coverage, where the test is performed, and laboratory fees. There may also be a fee for the health professional who draws your blood.
You can speak with your doctor or insurance company about the expected costs. They may be able to provide information about out-of-pocket expenses such as copays or deductibles.
If you do not have insurance, it may be helpful to talk with your doctor or an administrator at the facility where you receive treatment about the cost of testing and how to pay for it.
Taking a Lithium Test
A test to measure lithium levels is performed on a blood sample. Usually, your blood will be drawn in a medical office or laboratory, and the sample will be sent to a lab for analysis.
Point-of-care testing is another method of measuring lithium levels. Blood is collected from your finger and is immediately analyzed with a small device. You can speak with your doctor about whether point-of-care testing may be available. For more information about this, see our Point-of-Care Testing page.
Before the test
Lithium testing should take place 10 to 12 hours after your last dose of the medication. Sample collection most often takes place in the morning before you take the next dose of lithium. Generally, no other special test preparation is needed.
During the test
A sample of blood is required to measure lithium levels. Blood draws are a routine medical procedure and take just a few minutes. Usually, blood is drawn from a vein in your arm.
The health professional drawing your blood will start by placing a tourniquet around your upper arm to increase the amount of blood in the vein. Next, the area will be cleaned with an antiseptic wipe to prevent infection. A needle will be inserted into the vein to remove blood. When the collection is complete, the needle will be removed.
You might feel a slight sting or minor pain when the needle is inserted and removed, but this should last only a few moments.
If point-of-care testing is available, a drop of blood will be collected from your fingertip. A small device is used to analyze the sample, providing test results within a few minutes.
After the test
After the needle is removed from your vein, pressure will be applied to the area using a piece of cotton or gauze. This will help stop any bleeding and reduce the risk of bruising. A bandage will be placed over the area.
There is very little risk involved with the blood draw required to test lithium levels. You may have light bruising or soreness in your arm. Contact your doctor if you have severe pain or any signs of an infection after the test.
Lithium Test Results
Receiving test results
If you undergo a blood draw to measure your lithium levels, the laboratory will usually make the results available to your doctor within a few days. Your doctor may contact you directly to review the results and any next steps. In some cases, your doctor’s office may upload your results to an online medical portal or send them to you through the mail.
If you undergo point-of-care testing to check your lithium levels, your results will be available within minutes.
Interpreting test results
Your test report will show your lithium level in mmol/L. Established reference ranges for lithium are as follows:
- Therapeutic range: 0.6–1.2 mmol/L
- Toxic level: Greater than 1.5 mmol/L
The therapeutic range includes the levels at which lithium treatment is effective in managing the symptoms of bipolar disorder and other conditions. If your level falls below the therapeutic range, it may mean you are not receiving enough medication. Your doctor may want to adjust your lithium dose to reach a blood lithium concentration within the therapeutic range.
The dose of lithium necessary to achieve a blood concentration within the therapeutic range can vary depending on the individual. Lithium treatment is prescribed only after considering your symptoms and evaluating other aspects of your health. The results of a lithium test can then be interpreted in relation to your specific situation.
For example, certain medications and health conditions can impact how your body processes lithium and the amount needed to reach a level within the therapeutic range. Your doctor can account for these factors along with your lithium test results when determining the optimal dose for your treatment.
Lithium testing can also check for lithium poisoning. Levels above 1.5 mmol/L are an indication of lithium toxicity. Your health care provider will talk with you about the next steps if you are experiencing lithium toxicity.
If you have questions about your lithium levels, you can speak with your doctor about the test, your results, and what they mean for your physical and mental health.
You may have questions about lithium testing throughout the course of your treatment. The following questions may help you better understand your test results and the role of lithium testing in your care:
- How often will my lithium levels be checked?
- Which member of my health care team will be monitoring my lithium levels?
- Do I need other tests to assess my overall health?
- What symptoms might indicate lithium toxicity?
- What steps should I take if I have taken too much lithium?
Resources
Sources
A.D.A.M. Medical Encyclopedia. Lithium Toxicity. Updated November 13, 2021. Accessed September 29, 2022. https://medlineplus.gov/ency/article/002667.htm
American Board of Internal Medicine. ABIM Laboratory Test Reference Ranges. Updated January 2022. Accessed September 29, 2022. https://www.abim.org/Media/bfijryql/laboratory-reference-ranges.pdf
Chokhawala K, Lee S, Saadabadi A. Lithium. In: StatPearls. Updated July 11, 2022. Accessed September 29, 2022. https://www.ncbi.nlm.nih.gov/books/NBK519062/
Janicak PG. Bipolar Disorder in Adults and Lithium: Pharmacology, Administration, and Management of Adverse Effects. In: Keck P, ed. UpToDate. Updated August 9, 2022. Accessed September 29, 2022. https://www.uptodate.com/contents/bipolar-disorder-in-adults-and-lithium-pharmacology-administration-and-management-of-adverse-effects
UpToDate. Lithium: Drug Information. Lexicomp. Date unknown. Accessed September 29, 2022. https://www.uptodate.com/contents/lithium-drug-information
MedlinePlus: National Library of Medicine. Therapeutic Drug Monitoring. Updated September 16, 2021. Accessed September 29, 2022. https://medlineplus.gov/lab-tests/therapeutic-drug-monitoring/
Perrone J, Mudan A. Lithium Poisoning. In: Hendrickson, RG, ed. UpToDate. Updated August 10, 2022. Accessed on September 29, 2022. https://www.uptodate.com/contents/lithium-poisoning
