Phosphorus, Serum (Mass Concentration)
This test measures the amount of phosphorus, a mineral essential for healthy bones and cells, in your blood serum. Phosphorus helps maintain energy levels and supports normal cell function.
["Your blood phosphorus levels can indicate bone health and metabolic balance."]
Key facts at a glance
- LOINC
- 27123-9
- Short code
- Phosphate RBC-mCnt
- Synonyms
- Phosphate RBC-mCnt
- Category
- electrolyte
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 2.5
- Ref high
- 4.5
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84100
- SNOMED
- 900000000000003001
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Doctors may order a serum phosphorus test to check for conditions affecting bone metabolism, kidney function, or mineral balance. It can also help diagnose or monitor diseases like hyperparathyroidism, kidney disease, or metabolic disorders.
What to Expect Before the Test
No special preparation is needed for this test. You may have a small needle inserted into a vein in your arm, and a small amount of blood will be drawn. This process usually takes a few minutes and is generally painless.
What the Results Mean
While specific reference ranges vary by lab, abnormal levels may suggest issues like low phosphorus (hypophosphatemia) or high phosphorus (hyperphosphatemia). Your doctor will interpret results in the context of your overall health and symptoms.
Common Conditions Monitored
Serum phosphorus levels are often checked in patients with kidney disease, where phosphorus can build up due to impaired excretion. It may also be monitored in those with conditions affecting bone density, such as osteoporosis or metabolic bone diseases.
Reference range
Adult: 2.5-4.5 mg/dLN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: Abnormally low or high phosphorus levels can disrupt normal bodily functions, including bone health, muscle function, and energy production. Doctors use these results to guide treatment for conditions like kidney disease, metabolic disorders, or hormonal imbalances.
Short name
Serum Phosphorus
Frequently asked questions
What causes abnormal phosphorus levels?
How is phosphorus related to kidney function?
Can diet affect phosphorus levels?
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