Use

This test measures the amount of vitamin A (retinol)—the primary form circulating in blood—to assess both deficiency and excess. Vitamin A supports vision (especially in low light), immune function, skin and tissue health, and mucous membranes. Deficiencies may cause vision changes, increased infection risk, or skin/tissue issues, often in malabsorption conditions like celiac disease or IBD. Excess levels, typically from supplements, may result in adverse effects like headaches, blurred vision, nausea, or dizziness.