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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. Low levels may indicate poor absorption, certain medical conditions, or increased vitamin C loss through urine.

Quick summary

["Vitamin C helps protect cells from damage and supports immune function; low levels may signal underlying health concerns."]

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

Key facts at a glance

LOINC
31024-3
Short code
VGCC Ab Ser-sCnc
Synonyms
VGCC Ab Ser-sCnc
Category
electrolyte
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 Is This Test Done?

Your healthcare provider may order this test to check for vitamin C deficiency, assess nutrient absorption issues, or evaluate conditions like scurvy, chronic kidney disease, or malabsorption disorders. It may also be used in research or specialized clinical studies.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the blood draw if your test involves serum/plasma. Avoid smoking or consuming vitamin C supplements for 24 hours prior if instructed.

What Happens During the Test

A healthcare professional will draw blood from a vein in your arm. The sample is then sent to a lab for analysis using an immunoassay (IA) or similar method to detect vitamin C concentration.

What the Results Mean

Results are typically reported as a mass concentration (e.g., mg/dL or µmol/L). While reference ranges vary by lab, very low levels may indicate deficiency, while very high levels could suggest overconsumption or certain medications.

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 deficiency?
Vitamin C deficiency is rare in healthy individuals but can result from poor diet (e.g., limited citrus fruits, bell peppers), malabsorption disorders, chronic kidney disease, or excessive vomiting/diarrhea. Smoking also depletes vitamin C levels.
How long does it take to get results?
Results are usually 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?
While supplements may temporarily boost levels, they don’t address underlying causes of deficiency. Always consult your healthcare provider before changing supplements, as high doses can cause side effects or interfere with other medications.
  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