Pyridoxal 5'-phosphate (PLP) in serum/plasma
This test measures the active form of vitamin B6 (pyridoxal 5'-phosphate) in your blood. It helps assess whether your body has enough vitamin B6 to function properly.
["PLP levels can indicate vitamin B6 status and potential deficiencies."]
Key facts at a glance
- LOINC
- 39786-9
- Short code
- Vit B6 SerPl-sCnc
- Synonyms
- Vit B6 SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 of vitamin B6 deficiency, such as nerve problems, anemia, or unusual skin changes. It may also be used to monitor vitamin B6 levels in people taking supplements or those with certain medical conditions that affect vitamin metabolism.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for a few hours before the blood draw, but this depends on your provider’s instructions. Bring any medications or supplements you’re taking to your appointment.
How the Test Works
A small sample of blood is drawn from a vein in your arm. The blood is then sent to a lab where it is analyzed to measure the amount of pyridoxal 5'-phosphate in your serum or plasma.
What the Results Mean
Results are compared to reference ranges for healthy individuals. Low levels may suggest a vitamin B6 deficiency, while higher levels might indicate over-supplementation or certain metabolic conditions. Your provider will discuss these results with you in the context of your overall health.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low pyridoxal 5'-phosphate levels can indicate a vitamin B6 deficiency, which may lead to neurological issues, anemia, or weakened immune function. Conversely, very high levels might suggest excessive vitamin B6 intake or rare metabolic disorders. This test is particularly useful for monitoring patients on vitamin B6 supplements or those with conditions like pregnancy, alcoholism, or certain genetic disorders.
Short name
PLP Level
Frequently asked questions
What causes vitamin B6 deficiency?
What symptoms might I experience if my PLP levels are low?
How is PLP different from total vitamin B6?
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 16, 2026. · Read our editorial policy