Lithium

This test measures the amount of lithium in the blood. Lithium is one of the most well-established and widely-used drugs prescribed in the treatment of bipolar disorder. Bipolar disorder is a mental condition that is characterized by alternating periods of depression and mania. These periods may be as short as a few days or weeks or may be months or years long. 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 even out the moods 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. It is a relatively slow-acting drug and it may take several weeks to months for lithium to affect a person's mood. Dosages of the drug are adjusted until a steady concentration in the blood that is within therapeutic range is reached. 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, such as nausea, vomiting, diarrhea, confusion, and tremors. Extremely high levels can lead to stupor, seizures, and can be fatal.

A blood sample is obtained by inserting a needle into a vein in the arm.

No test preparation is needed. However, timing of the sample collection may affect results. Generally, lithium blood levels are performed 12-18 hours after the last dose (also known as a "trough" level). Tell the laboratorian who is drawing your blood when you took your last dose so that the results can be interpreted correctly.