Mouse Anti-25 OH Vitamin D3 monoclonal antibody for ELISA. Serum 25 OH Vitamin D3 (calcidiol) is the most stable circulating form of vitamin D and a low blood level suggests that a person is not getting enough exposure to sunlight or enough dietary vitamin D. Vitamin D deficiency, if severe, can lead to rickets (children) or osteomalacia (adults) and is linked to hyperparathyroidism, osteoporosis, and muscle weakness/pain. Prolonged vitamin D insufficiency leads to increased risk for multiple chronic conditions, including anemia, cardiometabolic and autoimmune diseases, depression, neurodegenerative/cognitive and sleep disorders, and some cancers.