Vitamin A (Retinol)
Measures vitamin A (retinol) levels in blood to assess nutritional status and detect deficiency or toxicity that may affect vision, immune function, and overall health.
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Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
What this test measures
This test measures the blood level of retinol, the active form of vitamin A that circulates in the bloodstream. Vitamin A also exists as provitamin A (beta-carotene) from plant sources, but retinol is the form the body uses directly, and it is what this test quantifies. Adequate retinol supports a range of essential functions including vision (particularly night vision and color perception), skin growth and repair, bone formation, immune defense, and reproductive health.
One important nuance of retinol testing is that the body works hard to keep blood levels stable by drawing on reserves stored in the liver. This means serum retinol can appear normal even as liver stores are declining, and it typically drops below the reference range only once those stores are nearly exhausted. Conversely, blood levels can remain in range even with moderate surplus. Healthcare providers factor in this buffering effect when interpreting results and may consider dietary history and clinical symptoms alongside the lab value.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals experiencing night blindness or difficulty seeing in low light conditions, as this may be an early sign of vitamin A deficiency that can progress to more serious vision problems.
- Those with dry eyes, dry skin, or frequent infections, since vitamin A plays a crucial role in maintaining healthy mucous membranes and supporting immune function.
- People with digestive disorders such as Crohn's disease, celiac disease, or liver disease that may impair absorption of fat-soluble vitamins like vitamin A.
- Individuals following restrictive diets or those with poor nutritional intake who may be at risk for vitamin A deficiency due to inadequate dietary sources.
- Those taking high-dose vitamin A supplements who want to monitor for potential toxicity, as excessive levels can cause serious health complications.
- Pregnant women or those planning pregnancy who need to ensure adequate but not excessive vitamin A levels, since both deficiency and excess can affect fetal development.
What to expect
Preparation
Fast for 12 hours before the test and avoid alcohol for 24 hours prior to collection. Schedule the blood draw for the morning before breakfast and before taking any medications. No vitamin supplements should be taken on the day of testing.
Sample Type
A healthcare professional will draw blood from a vein in the arm using a standard needle and collection tube. The process takes only a few minutes and involves minimal discomfort.
Collection
Visit any participating laboratory location during business hours. Check in at the front desk, and a phlebotomist will collect the blood sample. The sample will be protected from light and processed promptly to ensure accurate results.
Turnaround
Results are typically available within 2-5 business days after the laboratory receives the sample. Results will be securely delivered through the patient portal with no doctor visit required.
Understanding your results
Normal serum retinol levels generally fall between 20 and 60 micrograms per deciliter (mcg/dL), or approximately 0.69 to 2.09 micromoles per liter (μmol/L), though reference ranges may vary by laboratory. Values below 20 mcg/dL may indicate deficiency, while elevated values can suggest excessive intake or supplementation, which carries its own health risks since vitamin A is fat-soluble and can accumulate to toxic levels. Healthcare providers interpret results in the context of dietary habits, symptoms, liver function, and any conditions that may affect vitamin A absorption.
| Population | Reference Range | Notes |
|---|---|---|
| Adults | 20-60 mcg/dL (0.69-2.09 micromol/L) | Reference ranges established using fasting specimens and may vary slightly between laboratories |
Reference ranges may vary by laboratory and individual factors. Results should be interpreted by a healthcare provider in the context of your overall health.
What does a “Low” result mean?
Low vitamin A levels indicate a deficiency that can lead to night blindness and other complications. Symptoms of vitamin A deficiency may include difficulty seeing in low light or darkness, dry skin and hair, and weakened immune system making individuals more susceptible to infections. Vitamin A deficiency may occur when the body has trouble absorbing fats through the digestive tract, which can happen with certain medical conditions.
What does a “High” result mean?
High vitamin A levels typically indicate too much vitamin A circulating in the blood, which may lead to toxicity. Excessive vitamin A, usually from supplements or medications, can cause dizziness, headaches, nausea, and in serious cases may lead to coma or be life-threatening. In pregnant women, too much vitamin A can cause birth defects. Vitamin A toxicity can be dangerous and may cause symptoms including nausea, headaches, dizziness, and in severe cases, organ damage.
Privacy & confidentiality
All vitamin A test results are completely confidential and HIPAA-compliant. Results are delivered securely through your private patient portal and are never shared with insurance companies, employers, or added to your medical record without your consent. No doctor visit required for testing.
Frequently asked questions
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View TestLast reviewed: April 2026
CPT Code: 84590
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
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