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Phosphorus (Phosphate) Level in Serum or Plasma

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

This test measures the amount of phosphorus, a mineral essential for healthy bones and cells, in your blood.

Quick summary

["Phosphorus levels help assess bone health and metabolic function."]

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

Key facts at a glance

LOINC
57349-3
Short code
Phosphate 2h Ur-mCnc
Synonyms
Phosphate 2h 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 Is This Test Done?

Your doctor may order this test to check for conditions affecting phosphorus balance, such as kidney disease, vitamin D deficiency, or metabolic disorders. It can also help monitor treatment for conditions like hyperparathyroidism or hypophosphatemia.

What Does a Result Mean?

Results may indicate whether your body is absorbing phosphorus properly or if there’s an imbalance due to underlying health issues. However, reference ranges can vary by lab and individual health status.

Common Conditions Monitored

This test is often used to diagnose or manage conditions like chronic kidney disease, malnutrition, or metabolic bone diseases. It may also be part of routine monitoring for patients on certain medications or with metabolic disorders.

Sample Collection and Preparation

A blood sample is typically drawn from a vein in your arm. The test measures phosphorus levels in either serum (liquid part of blood after clotting) or plasma (liquid part of blood without clotting). Avoiding certain foods or medications for a few days before testing may help ensure accurate results.

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.

◆Associated findings1

Short name

Phosphorus

Frequently asked questions

What Are the Possible Causes of Abnormal Results?
Low phosphorus levels (hypophosphatemia) may be caused by kidney problems, excessive loss of phosphorus through urine, or conditions like malnutrition or overuse of certain medications. High phosphorus levels (hyperphosphatemia) can result from kidney failure, certain cancers, or overuse of phosphate supplements.
How Does This Test Fit Into My Health Plan?
Your doctor may use phosphorus test results to guide treatment for conditions like kidney disease, bone disorders, or metabolic imbalances. Regular monitoring helps adjust medications or lifestyle changes to keep levels within a healthy range.
Can I Prepare for This Test?
Yes, follow your doctor’s instructions carefully. Avoid consuming high-phosphorus foods (like dairy, nuts, or processed meats) for a few days before testing if advised. Drink plenty of water unless instructed otherwise.
  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