Urine Lithium-to-Creatinine Ratio
A urine test that compares the amount of lithium with the amount of creatinine, helping assess lithium excretion and kidney handling.
["This ratio can help clinicians evaluate lithium levels, kidney handling, and possible lithium-related medication effects."]
Key facts at a glance
- LOINC
- 34331-9
- Short code
- Lithium/Creat Ur-sRto
- Synonyms
- Lithium/Creat Ur-sRto
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 0.6
- Ref high
- 1.2
- Critical range
- — – 1.6 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This test measures lithium and creatinine in a urine sample and compares their amounts as a lithium-to-creatinine ratio. Creatinine is used as a marker of how much urine was produced.
Why might I need this test?
Your clinician may use this test to assess how your kidneys are eliminating lithium, particularly when monitoring treatment with lithium for a mood disorder. It may be used with blood tests to evaluate medication levels, kidney function, adherence, or signs of lithium toxicity.
How is the test performed?
A urine sample is collected and tested in a laboratory to determine the lithium and creatinine amounts. The results are then expressed as a ratio. Your clinician may compare this result with your blood lithium level and other kidney tests.
How do I prepare for the test?
Follow your clinician's or laboratory's instructions about when and how to collect the urine sample, including whether a timed collection is required. Take lithium exactly as prescribed unless your clinician tells you otherwise, and tell the laboratory if you have recently changed your dose or have kidney problems.
Reference range
Therapeutic: 0.6-1.2 mmol/LN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Urine Lithium-to-Creatinine Ratio
Frequently asked questions
Is this the same as a blood lithium test?
Does the test show whether I am having a lithium reaction?
Will I need to collect urine for a set period?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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