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Phosphorus concentration in serum/plasma

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

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

Quick summary

["Your blood phosphorus levels help doctors assess bone health and metabolic function."]

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

Key facts at a glance

LOINC
13539-2
Short code
Phosphate Ur-sCnc
Synonyms
Phosphate Ur-sCnc
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 It’s Done

Doctors may order this test to check for conditions affecting phosphorus balance, such as kidney disease (which often leads to phosphorus buildup) or conditions like hyperparathyroidism or malnutrition. It can also be part of routine monitoring for patients on certain medications or those with metabolic disorders.

What to Expect

A small blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it’s quick. No special preparation is needed unless instructed otherwise.

What the Results Mean

Phosphorus levels can vary based on diet, kidney function, and other health factors. High or low levels may signal underlying issues that need further evaluation.

Common Conditions Affecting Results

High phosphorus levels (hyperphosphatemia) can occur with kidney disease, certain cancers, or overuse of supplements. Low levels (hypophosphatemia) may result from malnutrition, excessive sweating, or certain medications.

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

Serum Phosphorus

Frequently asked questions

What causes abnormal phosphorus levels?
Abnormal phosphorus levels can result from kidney problems (like chronic kidney disease), certain medications (e.g., phosphate binders or diuretics), or conditions like hyperparathyroidism, malnutrition, or excessive vitamin D intake.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your doctor will contact you once they’re ready.
Can diet affect phosphorus test results?
Yes, diet plays a role. High-phosphorus foods (like dairy, nuts, and processed foods) can temporarily raise levels, while low-phosphorus foods (like lean meats and fruits) may lower them. Your doctor may advise dietary adjustments if needed.
  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