Phosphorus (Serum) Mass Concentration
This test measures the amount of phosphorus, a mineral essential for healthy bones, cells, and energy production, in your blood serum.
["Phosphorus levels help assess bone health and metabolic function."]
Key facts at a glance
- LOINC
- 30544-1
- Short code
- Phosphate TPN-mCnc
- Synonyms
- Phosphate TPN-mCnc
- 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 healthcare provider may order this test to check for conditions affecting phosphorus balance, such as kidney disease (which can cause phosphorus buildup), vitamin D deficiency, or metabolic disorders. It may also be part of routine monitoring for patients on certain medications or undergoing treatments like dialysis.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a metabolic panel. Bring any medications or supplements you’re taking to your appointment.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure is quick and typically painless. The blood sample is sent to a lab for analysis.
What Are Possible Results?
Results are reported as a mass concentration (typically in milligrams per deciliter, mg/dL). While reference ranges vary by lab, abnormally high or low levels may signal underlying health concerns.
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.
Low phosphorus levels (hypophosphatemia) can lead to muscle weakness, bone pain, or fatigue, while high levels (hyperphosphatemia) may indicate kidney dysfunction, overuse of phosphate-containing supplements, or certain metabolic disorders. Chronic imbalances can affect bone density, muscle function, and overall energy levels.
Short name
Serum Phosphorus Level
Frequently asked questions
What causes low phosphorus levels?
What causes high phosphorus levels?
Do I need to avoid certain foods before this test?
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