Vitamin A (retinol) test
Quick answer: This blood test measures vitamin A, which the body needs for vision, skin and immunity. It is ordered when deficiency is suspected, such as with night blindness, poor diet or gut absorption problems, or when too much is suspected from supplements.
- SampleBlood
- TakesAbout 5 minutes
- Before the testSome labs prefer a fasting sample; follow the lab's instructions.
How the test is done
- 1You may be asked to fast overnight if the lab prefers
- 2A vein in your arm is cleaned
- 3Blood is drawn into a tube that is protected from light
- 4A plaster is applied and you can eat afterwards
What your results can mean
Reading your report
Normal ranges differ between labs, so compare your result with the range printed on your report and discuss it with your doctor.
If the result is outside the usual range
A low level can be seen with poor diet, gut absorption problems, liver disease or zinc deficiency, and can cause night blindness and dry eyes. A high level is usually seen with too many supplements and can cause headache, skin changes and liver problems.
Who usually has this test
People with night blindness or dry eyes, poor diet or gut absorption problems, and those taking high-dose vitamin A supplements.
Risks and aftercare
You can eat and resume normal activities once the sample is taken.
Names and options
Also called: retinol test, serum vitamin A
Listed by the hospital as
- VITAMIN A, (retinol) SERUM
Questions about this test
Is too much vitamin A harmful in pregnancy?
Yes. High doses of vitamin A, especially from supplements or some acne medicines, can harm the developing baby. If you are trying to conceive or pregnant, check with your doctor before taking any vitamin A supplements.
What are signs of vitamin A deficiency?
Early signs include difficulty seeing in dim light and dry eyes. Deficiency can also make infections more likely, especially in children.
Why must the sample be protected from light?
Vitamin A breaks down in light, which can give a falsely low result. Labs usually wrap or shade the tube.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.