Vitamin A (Retinol)
Vitamin A is measured as retinol in your blood. It supports vision, immune function, skin, and healthy cell growth.
Vitamin A is essential for eyesight, especially in low light, and for a well-functioning immune system. Your body stores it, largely in the liver, and draws on those reserves as needed. Because blood levels are tightly regulated, retinol can stay fairly steady until stores are quite low or quite high.
A high retinol level can occur with excessive intake, usually from high-dose supplements or certain treatments. Because vitamin A is fat-soluble and stored in the body, sustained excess can build up and cause toxicity, with effects on the liver, bones, and, in pregnancy, the developing baby. A high result is a reason to review supplement use with a clinician.
A low retinol level suggests inadequate intake or absorption and, over time, can affect vision and immunity. It may reflect a limited diet or difficulty absorbing fats.
Most labs list a normal range, and both high and low values deserve attention given the storage and toxicity considerations. A clinician can help you interpret your result and supplement use.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.