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Vitamin C (Ascorbic Acid) in Serum or Plasma

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

This test measures the amount of vitamin C, an essential antioxidant found in your blood. Vitamin C helps protect cells from damage and supports immune function.

Quick summary

["Check your vitamin C levels to ensure your body has enough of this important nutrient."]

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

Key facts at a glance

LOINC
16409-5
Short code
Vit C p dose SerPl-mCnc
Synonyms
Vit C p dose SerPl-mCnc
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 Is Done

Doctors may order this test to evaluate vitamin C status in people with suspected deficiencies, chronic illnesses, or those who have trouble absorbing nutrients. It can also help monitor vitamin C levels in patients receiving high-dose vitamin C therapy or those with conditions like scurvy (vitamin C deficiency).

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 doctor’s instructions. Wear comfortable clothing and plan for the time it takes to get to the lab.

During the Test

A healthcare professional will insert a small needle into a vein in your arm to draw blood. You may feel a slight pinch, but it typically only takes a few minutes. The blood sample will be sent to a lab for analysis.

Possible Results and Interpretation

Results are compared to reference ranges that vary by lab and individual factors like age, sex, and health status. Low levels may indicate deficiency, while high levels could suggest recent vitamin C intake or certain medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum/Plasma Vitamin C Level

Frequently asked questions

How long does it take to get my vitamin C test results?
Results are typically available within 1–3 business days, depending on your lab and healthcare provider. Follow-up with your doctor to discuss the meaning of your results and any next steps.
Can I eat or drink anything before my vitamin C blood test?
Most tests do not require fasting, but some labs may ask you to avoid certain foods or supplements for 12–24 hours before your blood draw. Always check with your doctor or lab for specific instructions.
What does a low vitamin C level mean?
A low vitamin C level may signal a deficiency, which can affect your immune system, skin health, or energy levels. Your doctor may recommend dietary changes, supplements, or further testing to identify the cause, such as poor absorption or chronic illness.
  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