Skip to content

Phosphorus (Phosphate) 24-Hour Urinary Excretion Rate

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

This test measures how much phosphorus (a mineral) is excreted in your urine over a 24-hour period. It helps assess kidney function and phosphate balance in your body.

Quick summary

["This test helps evaluate kidney health and phosphate metabolism."]

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

Key facts at a glance

LOINC
58993-7
Short code
Phosphate 18h Ur-mRate
Synonyms
Phosphate 18h Ur-mRate
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 Is This Test Done?

Your healthcare provider may order this test if they suspect kidney disease, abnormal phosphate levels, or conditions like hyperphosphatemia (too much phosphorus in the blood). It can also help diagnose metabolic bone diseases or monitor phosphate levels in patients with chronic kidney disease.

What Does the Test Involve?

You’ll collect all your urine for a full 24-hour period in a special container. The test measures the total amount of phosphorus excreted in that urine sample.

How Is the Test Performed?

No special preparation is needed, but you’ll need to collect every bit of urine for 24 hours, including at night. Your sample is then sent to a lab for analysis.

What Do the Results Mean?

Results help determine if your kidneys are properly filtering phosphorus or if phosphate levels are outside normal ranges. Abnormal results may indicate kidney dysfunction or other metabolic issues.

Reference range

Adult: 2.5-4.5 mg/dLN/A

Specimen: urine

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.

This test is clinically significant for diagnosing or monitoring conditions affecting phosphate metabolism, kidney function, or metabolic bone disorders. Low or high urinary phosphate excretion may signal underlying kidney disease, dietary imbalances, or other systemic conditions.

Short name

24-Hour Urine Phosphate

Frequently asked questions

What are the normal ranges for this test?
Normal ranges can vary by lab and individual, so your results will be interpreted by your healthcare provider based on your specific health needs.
How often should I get this test?
Your doctor will determine how often you need this test based on your medical history, symptoms, and ongoing health conditions.
Can I eat or drink anything before the test?
No special diet is required, but you should collect all urine for the full 24-hour period without missing any samples.
  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