Vitamin A is a fat-soluble vitamin that promotes normal vision, contributes to growth of bone, teeth, and soft tissues and helps maintain skin and mucous membranes. Vitamin A also supports the formation of thyroid hormone and helps to fight infections.
This test does not measure beta carotene, the precursor to vitamin A (the active form). An 8 to 12 hour fast is required for this blood test. No foods or supplements containing vitamin A should be ingested in the previous 48 hours leading up to the test. Take all medications as prescribed.