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Lithium concentration in serum/plasma

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of lithium, a medication, in your blood. Lithium is often used to treat certain mental health conditions.

Quick summary

["Lithium levels help doctors monitor your medication dose and prevent potential side effects."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
13455-1
Short code
Lithium SerPl/RBC Bld
Synonyms
Lithium SerPl/RBC Bld
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test if you’re taking lithium to manage conditions like bipolar disorder, mania, or certain types of depression. It helps ensure your medication is at the right level to stay effective without causing harmful side effects.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re on lithium, your doctor may check levels more often during treatment adjustments.

What the Results Mean

Results are compared to a general reference range, but exact values can vary by lab. Too much lithium can cause nausea, confusion, or kidney problems, while too little may mean your medication isn’t working properly.

Common Causes of Abnormal Results

High levels may occur if you’re taking too much lithium, have poor kidney function, or are dehydrated. Low levels could happen if you’re not taking your medication as prescribed or if your body is excreting it too quickly.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Lithium Level

Frequently asked questions

Why might my lithium level be checked more often?
If you’re newly started on lithium, during dose adjustments, or if you have kidney issues, your doctor may check your levels more frequently to avoid dangerous buildup.
What should I do if my lithium level is too high?
Seek medical attention immediately. High lithium levels can be life-threatening and require prompt treatment, such as adjusting your dose or supportive care.
Can diet affect lithium levels?
Dietary changes alone won’t significantly alter lithium levels, but staying hydrated and avoiding excessive salt intake may help your kidneys process the medication better.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy