Phosphorus (Serum/Plasma) Concentration
This test measures the amount of phosphorus, a mineral essential for healthy bones, cells, and energy production, in your blood.
["Phosphorus helps maintain bone strength and supports normal cell function; low or high levels may signal underlying health concerns."]
Key facts at a glance
- LOINC
- 55973-2
- Short code
- Phosphate Prt-sCnc
- Synonyms
- Phosphate Prt-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 to check for conditions affecting phosphorus balance, such as kidney disease (which regulates phosphorus), metabolic disorders, or nutritional deficiencies. 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 needed unless instructed by your healthcare provider. You may have blood drawn from a vein in your arm, similar to other blood tests. If you’re on a low-phosphorus diet, follow your doctor’s guidance to avoid misleading results.
What the Results Mean
Phosphorus levels can vary based on health status, diet, and other factors. While reference ranges differ by lab, very low levels may indicate conditions like malnutrition or kidney problems, while very high levels could signal overactive parathyroid gland or kidney failure. Always discuss results with your doctor.
Common Conditions Affecting Phosphorus Levels
Conditions like chronic kidney disease, hypoparathyroidism (low thyroid hormone affecting phosphorus), or certain cancers may alter phosphorus levels. Medications (e.g., phosphate binders for kidney disease) or dietary intake (e.g., excessive dairy or nuts) can also influence results.
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.
Phosphorus levels are critical for bone health, nerve function, and energy metabolism. Abnormal results may signal kidney dysfunction, metabolic disorders, or endocrine imbalances that require medical evaluation and treatment.
Short name
Phosphorus Level
Frequently asked questions
What causes low phosphorus levels?
What causes high phosphorus levels?
How often should I get 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