Lithium CPT: 80178

Expected Turnaround Time

Within 1 day

Specimen Requirements




1 mL

Minimum Volume

0.5 mL


Red top


1. Draw blood 8 to 12 hours after last dose (trough specimen).

2. Serum gel tubes should be centrifuged within 2 hours of collection.

3. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.

Additional Information: Peak serum concentrations do not correlate with symptoms.

Storage Instructions

Maintain specimen at room temperature.

Stability Requirements

Temperature Period
Room Temperature8 hours
Refrigerated24 hours
Frozen6 months
Freeze/thaw/ cycles stable x 3

Patient Information

To measure lithium levels in the blood in order to determine the therapeutic level when just starting lithium medication; to monitor levels to ensure they are maintained in the therapeutic range; and sometimes to determine lithium toxicity

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) levels

A blood sample drawn from a vein.

No test preparation is needed. However, timing of the sample collection may affect results. Generally, lithium blood levels are measured 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.