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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, a water-soluble antioxidant found in your blood. Low levels may indicate poor absorption, dietary deficiencies, or health conditions affecting vitamin metabolism.

Quick summary

["Vitamin C supports immune function and helps prevent oxidative stress."]

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

Key facts at a glance

LOINC
32789-0
Short code
Visc Smn Ql
Synonyms
Visc Smn Ql
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 Might You Need This Test?

Your healthcare provider may order this test if you have symptoms of vitamin C deficiency (like fatigue, frequent infections, or bruising), suspect malabsorption issues, or are taking certain medications that can deplete vitamin C levels. It may also be checked during pregnancy, in chronic illness, or after certain surgeries.

What to Expect Before the Test

No special preparation is needed. You may have blood drawn from a vein in your arm. If you’re taking medications that affect vitamin C (like some antibiotics or diuretics), let your provider know.

What the Results Mean

Results help assess whether your vitamin C levels are within a healthy range. Very low levels may signal underlying health concerns that need attention, while very high levels (rare) could indicate over-supplementation or certain conditions.

Common Reasons for Testing

Doctors often check vitamin C levels to diagnose or monitor conditions like scurvy (vitamin C deficiency), certain cancers, or to evaluate how well your body absorbs nutrients.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin C Level

Frequently asked questions

What causes low vitamin C levels?
Low vitamin C levels can result from poor diet (not eating enough fruits/vegetables), smoking, heavy alcohol use, certain medications, or medical conditions like Crohn’s disease or celiac disease. Rarely, genetic disorders or kidney issues may also contribute.
What does it mean if my vitamin C level is low?
Low levels may increase your risk of infections, slow wound healing, or contribute to fatigue. Your provider may recommend dietary changes, supplements, or further testing to identify the cause.
Can vitamin C levels be affected by diet?
Yes! Eating foods rich in vitamin C (like citrus fruits, bell peppers, or broccoli) can help maintain healthy levels. However, vitamin C is water-soluble, so excess isn’t stored in the body—it’s mostly excreted through urine.
  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