Used primarily in medical and nutritional fields to assess and manage vitamin D status in individuals. It serves as a key biomarker for diagnosing deficiencies or excesses of vitamin D, aiding in the treatment of conditions like rickets, osteoporosis, and other bone disorders. Additionally, it is utilized in research studies to understand the role of vitamin D in immune function, cardiovascular health, and chronic disease prevention. In dietary supplements, it helps maintain optimal vitamin D levels, supporting overall health and well-being.