Phosphorus (Serum) Concentration
This test measures the amount of phosphorus, an essential mineral, in your blood serum. Phosphorus helps maintain healthy bones and teeth and is vital for energy production in your body.
["Your blood phosphorus levels can indicate whether you have conditions affecting bone health or metabolic function."]
Key facts at a glance
- LOINC
- 14879-1
- Short code
- Phosphate SerPl-sCnc
- Synonyms
- Phosphate SerPl-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 This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like muscle weakness, bone pain, or kidney issues. It could also be part of routine checks for patients with conditions like diabetes, metabolic disorders, or those on certain medications that affect phosphorus levels.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s part of a metabolic panel, but always confirm with your provider. Bring any medications you’re taking to discuss with them.
What the Test Involves
A blood sample is drawn from a vein, typically in your arm. The process is quick and usually painless. The sample is sent to a lab for analysis to measure phosphorus concentration.
What the Results Mean
Results are compared to a reference range specific to your lab. Low or high levels may signal underlying health concerns, such as kidney disease, vitamin D deficiency, or certain metabolic disorders. Your provider will interpret the results in the context of your overall health.
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
Serum Phosphorus
Frequently asked questions
What causes low phosphorus levels?
What causes high phosphorus levels?
How is phosphorus related to other tests?
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