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Test Code LITH Lithium, Serum

Method Name

Colorimetric

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

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 the serum aliquoted into a plastic vial within 2 hours of collection.

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


Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  28 days
  Ambient  72 hours

Reject Due To

Gross hemolysis Reject

Clinical Information

Lithium alters the intraneuronal metabolism of catecholamines by an unknown mechanism. It is used to suppress the manic phase of manic-depressive psychosis.

 

Lithium is distributed throughout the total water spaces of the body and is excreted primarily by the kidney.

 

Toxicity from lithium salts leads to ataxia, slurred speech, and confusion. Since the concentration of lithium in the serum varies with the time after the dose, blood for lithium determination should be drawn at a standard time, preferably 8 to 12 hours after the last dose (trough values).

Reference Values

Therapeutic: 0.5-1.2 mmol/L (trough concentration)

Critical value: >1.6 mmol/L

There is no relationship between peak concentration and degree of intoxication.

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 day

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

80178

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.