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Serum or plasma concentration of vitamin A (retinol)

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

This test measures the amount of vitamin A (a fat-soluble nutrient essential for vision, immune function, and cell growth) in your blood.

Quick summary

["Vitamin A helps protect your eyesight and supports your immune system."]

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

Key facts at a glance

LOINC
49374-2
Short code
HCV RNA Mar NAA+probe-Log#
Synonyms
HCV RNA Mar NAA+probe-Log#
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
CPT
86803
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 doctor may order this test to check if you have a vitamin A deficiency, which can cause vision problems, weakened immunity, or other health issues. It may also be used to monitor vitamin A levels in people with certain medical conditions or those taking supplements.

What does a low or high result mean?

Low levels might indicate poor absorption, liver disease, or malnutrition. High levels could suggest toxicity, especially if caused by supplements or certain medications.

How is the sample collected?

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch, but it won’t cause significant discomfort.

What should I do before the test?

Avoid taking large doses of vitamin A supplements for at least 48 hours before testing, as this could affect results. Follow any specific instructions your doctor provides.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin A is crucial for maintaining healthy vision, immune function, and skin integrity. Deficiencies can lead to night blindness, recurrent infections, or skin disorders. Excessive intake, particularly from supplements, may pose risks like liver damage or other toxicity symptoms.

Short name

Vitamin A level

Frequently asked questions

How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time.
Will I need to prepare for this test?
No special preparation is usually needed, but avoid alcohol or heavy meals 2 hours before the blood draw if instructed by your doctor.
Is this test painful?
The blood draw may cause a brief pinch, but most people describe it as mild discomfort. Local anesthesia can be used if needed.
  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