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Vitamin C (Ascorbic Acid) in Serum or Plasma

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

This test measures your body’s level of vitamin C, an essential antioxidant that helps protect cells and supports immune function.

Quick summary

["Vitamin C supports immunity and skin health; low levels may indicate poor absorption or health conditions."]

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

Key facts at a glance

LOINC
16408-7
Short code
Vit C Ur-mCnc
Synonyms
Vit C Ur-mCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters

Vitamin C is crucial for maintaining healthy skin, wound healing, and immune function. Low levels can sometimes signal underlying health issues, such as malabsorption or certain medical conditions.

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. If you’re on a blood thinner, let your provider know before the test.

What the Results Mean

Results help doctors assess whether your vitamin C levels are within a healthy range. Very low levels may prompt further evaluation for conditions like scurvy or digestive disorders.

Common Causes of Low or High Levels

Low vitamin C levels can occur due to poor diet, certain medications, or health conditions like Crohn’s disease. High levels are less common but may result from supplements or rare genetic disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin C Level

Frequently asked questions

What triggers a vitamin C test?
Your doctor may recommend this test if you have symptoms like fatigue, frequent infections, or slow-healing wounds, or if you’re taking certain medications that affect vitamin absorption.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time.
Can I take vitamin C supplements before the test?
Yes, but avoid taking large doses (e.g., megadoses) 24–48 hours before the test, as they may affect results.
  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