Potassium/Creatinine Ratio, 24-Hour Urine
Measures potassium relative to creatinine in urine collected for 24 hours to help assess how much potassium the kidneys are excreting.
["This 24-hour urine test helps evaluate renal potassium excretion and may support evaluation of abnormal potassium levels."]
Key facts at a glance
- LOINC
- 56143-1
- Short code
- Potassium/Creat 24h Ur-sRto
- Synonyms
- Potassium/Creat 24h Ur-sRto
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 3.5
- Ref high
- 5
- Critical range
- 2.5 N/A – 6.5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84132
- SNOMED
- 110742001
- 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 the amount of potassium in a 24-hour urine collection relative to the amount of creatinine. Creatinine is used as a marker of urine volume and muscle breakdown.
Why might I need this test?
A clinician may order it to assess kidney potassium excretion, particularly when blood potassium is unexpectedly low or high, or when medication or kidney function may be affecting electrolyte balance.
How is the test performed?
You collect all urine for exactly 24 hours in the container provided by the laboratory. The total volume is recorded, and a sample is analyzed to calculate the potassium-to-creatinine ratio.
How do I prepare for the test?
Follow the laboratory's collection instructions and record the collection start and finish times. Keep the container refrigerated if instructed, avoid losing urine, and tell the laboratory about medicines or supplements that may affect potassium levels.
Reference range
Adult: 3.5-5.0 mmol/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A lower-than-expected ratio may indicate that the kidneys are not excreting enough potassium, which can occur with impaired kidney function or certain medications. A higher ratio may reflect increased potassium intake, kidney potassium loss, or other causes of altered electrolyte balance, so results must be interpreted alongside diet, medicines, and other laboratory tests.
Short name
24-hour urine potassium/creatinine ratio
Frequently asked questions
Why is creatinine included in this urine test?
How long do I need to collect urine?
Can medicines or supplements affect the result?
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 16, 2026. · Read our editorial policy