25（OH）-D is a prehormone that is produced in the liver by hydroxylation of vitamin D3 (cholecalciferol) by the enzyme cholecalciferol 25-hydroxylase. Physicians worldwide measure this metabolite to determine a patient's vitamin D status.

25(OH) D Rapid Quantitative Test (Chemiluminescence Immunoassay) is used for in vitro quantitative detection of the 25-hydroxyvitamin D (25 (OH) D) concentration in human serum, plasma that contains heparin /EDTA and other anticoagulants samples, mainly used for auxiliary diagnosis of health check.