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Serum/plasma concentration of vitamin C (ascorbic acid)

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 proper nutrient intake and health."]

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

Key facts at a glance

LOINC
86689-7
Short code
RVA Spec Ql Cult
Synonyms
RVA Spec Ql Cult
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
organism-specific-culture
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 healthcare provider may order this test to evaluate vitamin C levels if you have symptoms of deficiency (like fatigue, frequent infections) or if you’re taking supplements. It can also help monitor conditions affecting vitamin absorption or metabolism.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a fasting protocol. Bring a list of medications to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually takes only a few minutes. The blood is sent to a lab for analysis.

What Are Possible Results?

Results are compared to a reference range for healthy adults, though exact values can vary by lab. Low levels may indicate poor absorption, certain medical conditions, or excessive vitamin loss.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin C Level

Frequently asked questions

What causes vitamin C levels to be low?
Vitamin C deficiency can result from poor diet (e.g., limited fruit/vegetable intake), certain medications (like some antibiotics or diuretics), smoking, or medical conditions affecting absorption (e.g., celiac disease). Rarely, genetic disorders or kidney disease may also play a role.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your provider will contact you once they’re ready.
Can I take vitamin C supplements to raise my levels?
Yes, but consult your provider first. Overdosing can cause side effects like stomach upset or kidney stones. They may recommend a specific dose based on your test results and health status.
  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