What is a normal lithium level?

From the Guidelines

A normal therapeutic lithium level typically ranges from 0.6 to 1.2 milliequivalents per liter (mEq/L) or 0.6 to 1.2 millimoles per liter (mmol/L) in the blood. For acute mania treatment, levels are often maintained between 0.8 and 1.2 mEq/L, while for maintenance therapy, lower levels between 0.6 and 0.8 mEq/L are usually sufficient 1. Lithium has a narrow therapeutic window, meaning the difference between effective and toxic levels is small. Levels above 1.5 mEq/L can cause toxicity with symptoms including tremor, confusion, vomiting, diarrhea, and in severe cases, seizures or coma.

Key Considerations

• Regular blood monitoring is essential when taking lithium, typically every 3-6 months once stable, or more frequently if the dose changes or the patient is acutely unwell 1.
• Blood samples should be drawn 12 hours after the last dose (trough level) for accurate measurement.
• Factors like dehydration, reduced salt intake, certain medications (especially NSAIDs and diuretics), and kidney problems can increase lithium levels and risk of toxicity.
• It is also important to monitor glomerular filtration rate (GFR), electrolytes, and lithium levels, and to avoid using concomitant NSAIDs, as well as maintaining hydration during intercurrent illness 1.

Monitoring and Maintenance

• The risk-benefit of lithium in specific situations must be weighed, particularly in patients with chronic kidney disease (CKD) or those at risk of renal tubular dysfunction 1.
• Clinicians should be aware of the potential for lithium to cause renal tubular dysfunction with prolonged use, even at therapeutic levels, and monitor patients accordingly 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION ... Such doses will normally produce an effective serum lithium level ranging between 1 and 1. 5 mEq/L. ... The desirable serum lithium levels are 0. 6 to 1.2 mEq/l.

A normal lithium level is between 0.6 and 1.5 mEq/L, with 0.6 to 1.2 mEq/L being desirable for long-term control 2.

• For acute mania, the effective serum level ranges between 1 and 1.5 mEq/L.
• For long-term control, the desirable serum level ranges between 0.6 and 1.2 mEq/L.

From the Research

Normal Lithium Levels

• The normal lithium level is a topic of ongoing research and debate in the medical community 3, 4, 5, 6, 7.
• According to a 1980 study, the therapeutic range for lithium is suggested to lie between 0.30 and 1.30 mmoles/liter, with 1.50 mmoles/liter representing the lower limit of risk for intoxication 3.
• A 2009 study suggests that lithium concentrations should be maintained between 0.6 and 0.8 mmol/L, although some authors still favor 0.8-1.2 mmol/L 4.
• Another study published in 2023 found that the primary outcome of achieving therapeutically appropriate serum lithium levels between 0.4 and 1.0 mEq/L at 18 months after enrollment was achieved by 69.1% of patients in the reminder group and 60.0% of patients in the usual care group 5.
• A 1986 study concluded that the twelve-hour serum lithium value is essentially arbitrary and can only be used as an unambiguous guide in an intraindividual context, and that the daily dose should be individualized within wider parameters 6.
• A 1989 study compared standard and low serum levels of lithium for maintenance treatment of bipolar disorder and found that doses resulting in serum lithium levels from 0.8 to 1.0 mmol per liter are more effective in treating bipolar disorder than those that result in lower serum lithium concentrations 7.

Therapeutic Range

• The therapeutic range for lithium is generally considered to be between 0.6 and 1.2 mmol/L 4.
• However, some studies suggest that the therapeutic range may be narrower, between 0.8 and 1.0 mmol/L 7.
• The upper limit of the therapeutic range is generally considered to be around 1.5 mmol/L, above which the risk of intoxication increases 3.

Monitoring and Maintenance

• Regular serum lithium monitoring is recommended to ensure that lithium levels remain within the therapeutic range 5.
• The frequency of monitoring may vary depending on individual patient factors, such as age, kidney function, and dosage regimen 4.
• Maintenance therapy with lithium should be individualized to each patient, taking into account their unique needs and response to treatment 6, 7.