2-hydroxyvitamin D is the main form of vitamin D in vivo. Vitamin D is a steroid derivative, which belongs to fat soluble vitamin. Vitamin D is mainly synthesized by human skin after ultraviolet irradiation, and a small part is taken from food or supplements. Vitamin D not only affects the metabolism of calcium and phosphorus, but also has a wide range of physiological functions. It is an essential substance to maintain human health, cell growth and development, and is closely related to a variety of diseases. There are two forms of vitamin D in human body, vitamin D3 (cholecalciferol) and vitamin D2 (ergocalcitol). 2-Vitamin D is converted into 25 hydroxyvitamin D25- (OH) VD by hydroxylation in liver, and then into active 1, 25- dihydroxyvitamin D in kidney. The level of 25- (OH) VD in blood can reflect the storage level of vitamin D in human body, and it is related to the clinical symptoms of vitamin D deficiency. More and more epidemiological and laboratory evidences show that serum 25- (OH) d level is related to rickets, osteoporosis, Parkinson's disease, cardiovascular disease, hypertension, chronic kidney disease, type 2 diabetes and tumor in children. Therefore, the detection of 25 - (OH) VD is very important for the diagnosis and prevention of related diseases. STORAGE AND STABILITY 1. Store the detector buffer at 2～30℃. The buffer is stable up to 18 months. 2. Store AEHEALTH 25- (OH)VD Rapid Quantitative Test Cassette at 2～30℃, shelf life is up to 18 months. 3. Test Cassette should be used within 1 hour after opening the pack. PERFORMANCE CHARACTERISTICS Detection Limit: 5.0ng/ mL; Linear Range: 5.0-120.0ng/ mL; Linear correlation coefficient R ≥ 0.990; Precision: within batch C.V. is ≤ 15%; between batches C.V. is ≤ 20%; Accuracy: the relative deviation of the measurement results shall not exceed ± 15% when the standardized accuracy calibrator is tested.