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Vitamin C Phenolic Profile (Serum/Plasma)

Published: August 9, 2026Updated: August 16, 2026

This test measures the levels of vitamin C (ascorbic acid) and its breakdown products in your blood. Vitamin C is important for immune function, skin health, and antioxidant protection.

Quick summary

["Check if your body is producing enough vitamin C or if its breakdown is affecting your health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
61538-5
Short code
Vit C PhenX
Synonyms
Vit C PhenX
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenx
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 fatigue, frequent infections, or skin issues that could be linked to vitamin C deficiency or metabolic changes. It may also be used to monitor conditions affecting vitamin C metabolism, such as certain genetic disorders or chronic illnesses.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, similar to other routine blood tests. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results show the concentration of vitamin C and its phenolic metabolites in your blood. While reference ranges vary by lab, abnormal levels may indicate either excess breakdown or insufficient production of vitamin C.

Common Conditions Monitored

This test helps assess conditions like scurvy (vitamin C deficiency), certain metabolic disorders, or how well your body processes antioxidants. It may also be part of broader evaluations for immune dysfunction or oxidative stress.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin C Levels (Phenolic Metabolites)

Frequently asked questions

What causes vitamin C levels to change in this test?
Changes in vitamin C levels can be due to dietary intake, genetic factors affecting metabolism, certain medications, or underlying health conditions like liver disease or kidney problems. For example, excessive vitamin C intake or certain medications may alter its breakdown products.
How often should I get this test?
The frequency depends on your health status and symptoms. If you have a known condition affecting vitamin C metabolism, your provider may recommend regular monitoring. Otherwise, this test is usually ordered as needed for specific concerns.
Can I take supplements before the test?
Yes, but discuss it with your provider first. Vitamin C supplements may affect the test results, so timing your intake around the test date can help ensure accurate readings.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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