Sensitive ELISA for Vitamin D quantification.

• Measure vitamin D in plasma or serum
• Detect the metabolically stable forms 25(OH)D₃ and 25(OH)D₂
• Assay 24 samples in triplicate or 36 samples in duplicate
• Measure vitamin D levels down to 0.5 ng/ml
• Read: Colorimetric at 405 to 420 nm

The primary synthesis of functional vitamin D begins in the skin, where a cholesterol by-product acted upon by UV light forms vitamin D₃. Vitamin D₃ is carried through the bloodstream, attached to the vitamin D binding protein, to the liver where it is converted to 25-hydroxy vitamin D₃ (25(OH)D₃). This product is then transported to the kidney where it is further converted to 1,25-dihydroxycholecalciferol (1,25(OH)₂D₃), the biologically active form. Active 1,25(OH)₂D₃ is very short-lived and is rapidly metabolized to its deactivated forms.

Vitamin D Immunoassay, accurate Vitamin D measurement in plasma or serum. Vitamin D ELISA Kit is a competitive assay that can be used for Vitamin D quantification in plasma or serum. Because of the short half-life of the biologically active 1,25(OH)D form, this Vitamin D assay primarily detects the more metabolically stable forms, 25(OH)D₃ and 25(OH)D₂.

Accurate detection of these forms requires that they be displaced from the vitamin D binding protein prior to measurement. A simple, acetone-based purification protocol is included as the initial procedure of the Vitamin D assay kit for this purpose.