Back Blood-tests Explained
Lithium
At a Glance
Why Get Tested?
To measure lithium levels in the blood in order to determine the therapeutic level when just starting lithium medication; to maintain the therapeutic level or to determine lithium toxicity
When to Get Tested?
When beginning treatment with lithium as the dose is adjusted to achieve therapeutic blood levels; at regular intervals to monitor lithium levels; as needed to detect sub-therapeutic levels or high (toxic) concentrations
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
Lithium is a drug used as an antipsychotic in the treatment of bipolar disorder. Occasionally, it can be used in other disorders to augment an antidepressant that does not adequately treat a depression. This test measures the amount of lithium in the blood.
Bipolar disorder is a mental condition characterized by alternating periods of depression and mania. These periods may be as short as a few days or weeks or as long as months or years. During a depressive episode, those affected may feel sad, hopeless, worthless, and lose interest in daily activities. They may be fatigued but have trouble sleeping, experience weight loss or gain, have difficulty concentrating, and have thoughts of suicide. During a manic episode, those affected may be euphoric, irritable, have high energy and grandiose ideas, use poor judgment, and participate in risky behaviors. Sometimes affected people will have mixed episodes with aspects of both mania and depression. Bipolar disorder can affect both adults and children.
Lithium is prescribed to stabilize the mood swings of a person with bipolar disorder. It is often called a "mood stabilizer" and is sometimes prescribed for people with depression who are not responding well to other medications. Less commonly, lithium may be prescribed to prevent schizoaffective disorder and cluster headaches.
Because lithium is a relatively slow-acting drug, its effect on mood may take several weeks. Dosages of the drug are adjusted until blood concentrations are within a therapeutic range—the blood level range that achieves the desired effect and treats an individual's bipolar disorder. The actual amount of drug that it will take to reach this steady state will vary from person to person and may be affected by a person's age, general state of health, and other medications that they are taking.
Lithium levels are monitored on a regular basis because blood levels must be maintained within a narrow therapeutic range. Too little and the medication will not be effective; too much and symptoms associated with lithium toxicity may develop.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed. However, timing of the sample collection may affect results. Generally, lithium blood levels are performed 12 hours after the last dose (also known as a "trough" level). Tell the person who draws your blood when you took your last dose so that the results can be interpreted correctly.
The Test
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