Vitamin A (Retinol) reference ranges
| Group | Normal Range | Unit |
|---|
| Adults | 30–80 | mcg/dL (1.05–2.80 µmol/L) |
| Children (1–12 yrs) | 20–50 | mcg/dL |
| Deficiency | <20 | mcg/dL (<0.70 µmol/L) |
| Toxicity (hypervitaminosis A) | >100 | mcg/dL |
What is the Vitamin A blood test?
Serum Retinol
Vitamin A is measured as retinol in blood serum. The test is ordered when deficiency is suspected (night blindness, dry skin, recurrent infections) or when toxicity is a concern — for example, in people taking high-dose Vitamin A supplements or isotretinoin for acne. Because Vitamin A is fat-soluble and stored in the liver, levels reflect months of intake rather than a single meal. The test requires a fasting sample in some labs.
Symptoms of Vitamin A deficiency
| Symptom | Explanation |
|---|
| Night blindness | Earliest sign — difficulty seeing in dim light |
| Dry, rough skin (xerosis) | Vitamin A maintains skin cell turnover |
| Bitot's spots | Foamy white patches on the white of the eye |
| Recurrent infections | Vitamin A is critical for immune cell function |
| Poor wound healing | Reduced collagen synthesis without adequate Vitamin A |
| Infertility | Vitamin A is needed for reproductive function |
Vitamin A toxicity (hypervitaminosis A)
Can you have too much Vitamin A?
Yes — unlike water-soluble vitamins, excess Vitamin A is stored in the liver and can accumulate to toxic levels. Toxicity is almost always caused by over-supplementation (not food). Symptoms include headache, nausea, dizziness, blurred vision, bone pain, hair loss and, in severe cases, liver damage. Pregnant women must be especially careful — excess Vitamin A is teratogenic and can cause birth defects. Do not take more than the recommended dose without medical supervision.
Causes of low Vitamin A
| Cause | Mechanism |
|---|
| Poor dietary intake | Deficiency in foods rich in retinol (liver, dairy) and beta-carotene (orange/yellow vegetables) |
| Fat malabsorption | Vitamin A is fat-soluble — coeliac disease, Crohn's, cystic fibrosis reduce absorption |
| Liver disease | Liver stores and processes Vitamin A — cirrhosis impairs storage and conversion |
| Zinc deficiency | Zinc is needed to mobilise Vitamin A from the liver |
| Chronic infection / parasites | Infections increase Vitamin A utilisation |
Questions to ask your doctor
- Is my night vision poor — could that be a Vitamin A deficiency?
- Do I have a fat malabsorption condition that affects Vitamin A?
- Is my Vitamin A supplement dose safe?
- If I am pregnant, is my Vitamin A intake within safe limits?
Medical Disclaimer: This page is for general educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis, treatment, and personalised advice.