Retinol Blood Test in Idaho

What this test measures

Vitamin A refers to a group of related compounds, with retinol being the form most often measured in blood. It is essential for producing rhodopsin, a pigment in the retina that allows vision in low light. The nutrient also supports immune cell function and helps maintain the surface tissues of the eyes, airways, and skin.

The test typically measures serum retinol, sometimes reported alongside retinol-binding protein or beta-carotene. Because vitamin A is fat-soluble, it is stored in the liver, and blood levels can stay normal until stores are significantly depleted. Results can be affected by inflammation, liver disease, and recent intake, so interpretation needs context.

Deficiency is uncommon in well-nourished populations but can occur with malabsorption, restrictive diets, or certain medical conditions. Symptoms may include difficulty seeing in dim light, dry eyes, and increased susceptibility to infections. Excessive vitamin A is also possible and can cause other problems, so testing is used to look at both directions.