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Phosphorus (Phosphate) in Serum or Plasma

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

This test measures the amount of phosphate, a mineral important for energy production and bone health, in your blood.

Quick summary

["Phosphate levels help assess mineral balance and potential bone or kidney issues."]

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

Key facts at a glance

LOINC
25501-8
Short code
Phosphate Fld-sCnc
Synonyms
Phosphate Fld-sCnc
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
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
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test if you have symptoms like muscle weakness, bone pain, or kidney problems. It can also be checked during evaluations for conditions like hypophosphatemia (low phosphate) or hyperphosphatemia (high phosphate), or after treatments like chemotherapy or certain medications.

What Does a Result Mean?

Results can indicate whether your phosphate levels are too high or too low, which may signal underlying health concerns such as metabolic disorders, kidney disease, or nutritional deficiencies.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. The sample is sent to a lab where phosphate levels are measured using a specialized chemical test. Plasma or serum (liquid part of blood) is analyzed.

Common Conditions Monitored

Phosphate levels are monitored in patients with chronic kidney disease, those undergoing dialysis, or those receiving certain medications that can affect phosphate metabolism.

Reference range

Adult: 2.5-4.5 mg/dLN/A

Specimen: serum

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 Level

Frequently asked questions

What factors might affect my phosphate levels?
Several factors can influence phosphate levels, including diet (especially intake of foods like dairy, nuts, and organ meats), kidney function, certain medications (like antacids or chemotherapy drugs), and conditions like malnutrition or severe illness.
How soon will I get my results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing times. Your healthcare provider will discuss them with you during your follow-up visit.
Can I eat or drink anything before this test?
For most blood tests, including this one, you can eat and drink normally unless instructed otherwise by your doctor. However, fasting may not be required for this test, but always follow your healthcare provider’s specific instructions.
  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