Description
25-Hydroxyvitamin D (25(OH)D), also known as calcidiol, is the major circulating form of Vitamin D in the blood. It is a precursor to the active form of Vitamin D.
25(OH)D itself is not the active form but serves as the main storage form of Vitamin D in the body. It is the best indicator of Vitamin D status in the blood because of its relatively long half-life of about 2-3 weeks.
This test is not the same as Calcitriol (1,25 di-OH Vitamin D), which must be ordered separately.