24-Hour Urinary Phosphate Measurement
This test measures the total amount of phosphate, a mineral important for bone health and energy production, found in your urine over a full day.
["Helps assess kidney function and phosphate balance in your body."]
Key facts at a glance
- LOINC
- 21458-5
- Short code
- Phosphate 24h Ur-mCnc
- Synonyms
- Phosphate 24h Ur-mCnc
- Category
- electrolyte
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 2.5
- Ref high
- 4.5
- Critical range
- 1 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84100
- 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
Why This Test Is Done
Your doctor may order this test if they suspect kidney problems, such as chronic kidney disease, or if you have symptoms like bone pain, muscle weakness, or unusual fatigue. It can also help diagnose conditions like phosphate wasting or metabolic bone diseases.
How the Test Is Performed
You’ll collect all urine for a full 24-hour period in a special container. The sample is then sent to a lab for analysis.
What to Expect Before the Test
No special preparation is needed, but drink enough fluids to produce clear urine. Avoid certain medications or supplements that might affect phosphate levels without consulting your doctor.
What the Results Mean
Results help determine if your kidneys are properly filtering phosphate from your blood. Abnormal levels may indicate kidney dysfunction or other metabolic issues.
Reference range
Adult: 2.5-4.5 mg/dLN/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
Phosphate in urine (24-hour collection)
Frequently asked questions
What causes abnormal phosphate levels in urine?
How long does it take to get results?
Yes, your diet can influence phosphate levels. High-phosphate foods (like dairy, nuts, and processed foods) may temporarily raise urine phosphate. Your doctor may recommend dietary adjustments if needed, but avoid drastic changes without guidance.
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