Potassium/Creatinine Ratio, 24-Hour Urine
Measures the ratio of potassium to creatinine in urine collected over 24 hours, helping evaluate potassium excretion and kidney function.
["This test estimates how much potassium your body is losing in urine and how the kidneys are handling potassium."]
Key facts at a glance
- LOINC
- 56971-5
- Short code
- Potassium/Creat 24h Ur-Rto
- Synonyms
- Potassium/Creat 24h Ur-Rto
- 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 potassium and creatinine in a urine sample collected for 24 hours. The results are reported as a potassium-to-creatinine ratio, which compares potassium excretion with a marker of urine concentration.
Why might I need this test?
Your clinician may use this test to assess kidney handling of potassium, investigate abnormal potassium levels, or evaluate how potassium balance is affected by diet, medications, or certain hormonal conditions.
How is the test performed?
You collect all urine produced during a full 24-hour period. The laboratory then measures potassium and creatinine and calculates their ratio. The collection time and any missed samples can affect the result.
How do I prepare for the test?
Follow your laboratory's collection instructions, including the exact starting and ending times. Usually, you empty your bladder at the start time, collect every subsequent sample, and keep the container refrigerated or preserved as directed.
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 higher-than-expected ratio may indicate increased potassium loss in the urine, which can occur with certain kidney conditions, medications, or excess aldosterone activity. A lower-than-expected ratio may reflect reduced potassium excretion, potentially related to kidney function, low intake, or medications that retain potassium. Results should be interpreted with other laboratory tests, symptoms, diet, and medications.
Short name
24-Hour Urine Potassium/Creatinine Ratio
Frequently asked questions
Why is creatinine included in this urine test?
Does an abnormal result mean I have a kidney disease?
What if I miss part of the 24-hour urine collection?
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