The FinecareTM Vitamin D Rapid Quantitative Test Kit (often just called the Vitamin D reagent) is designed to measure total Vitamin D — specifically 25-hydroxyvitamin D [25(OH)D] levels in human blood. It uses fluorescence immunoassay technology and is used with a FinecareTM FIA Analyzer (such as FS-113, FS-114, or FS-205) to give quantitative results for clinical assessment of vitamin D status.