25-OH Vitamin D ELISA TEST KIT

INTENDED USE

     Detection Kit for 25-OH Vitamin D (Enzyme-Linked ImmunoSorbent Assay , ELISA).It is used in quantitative tests for Vitamin D in human serum.

SUMMARY AND CLINICAL SIGNIFICANCE

    Vitamin D is a fat-soluble  hormone precursor that is mainly produced in the skin by exposure to sunlight. Vitamin D is biologically inert and must undergo hydroxylation steps to become active. Our body can only synthesize vitamin D3. Vitamin D2 is taken up with fortified food or given by supplements. Physiologically, vitamin D3 and D2 are bound to the vitamin D-binding protein (VDBP) in plasma and transported to the liver to become 25-hydroxy vitamin D (25-OH vitamin D). As 25-OH vitamin D represents the major storage form, its blood concentration is used to assess the overall vitamin D status. More than 95 % of 25-OH vitamin D, measurable in serum, is 25-OH vitamin D3 whereas 25-OH vitamin D2 reaches measurable levels only in patients taking vitamin D2 supplements. Vitamin D is essential for bone health. In children, severe deficiency leads to rickets. In elderly, the risk of falling has been attributed to vitamin D deficiency due to muscle weakness. Moreover, low 25-OH vitamin D concentrations are associated with lower bone mineral density. Insufficiency has also been linked to diabetes, cancer, cardiovascular disease, and autoimmune diseases. Both dietary supplements of Vitamin D that are currently available in the market (Vitamin D2 and Vitamin D3) are converted to 25-OH Vitamin D in the liver. The sum of the concentrations of 25-OH Vitamin D2 and 25-OH Vitamin D3 in serum or plasma is referred to as “Total 25-OH Vitamin D”. Accurate monitoring of total 25-OH Vitamin D level is critical in clinical settings. Vitamin D deficient patients who are prescribed a daily Vitamin D supplement should regularly monitor their serum or plasma Vitamin D levels in order to reach an optimal level and prevent their 25-OH Vitamin D concentrations from reaching excessive levels that are considered toxic. The Vitamin D total assay employs special antibodies to capture both 25-hydroxyvitamin D3 and D2. This assay is intended for the quantitative determination of total 25-OH vitamin D in human serum and plasma, as an aid in the assessment of vitamin D sufficiency.

PRINCIPLE

The 25-OH Vitamin D Quantitative Test Kit is based on a solid phase enzyme-linked immunosorbent assay. The assay system utilizes one antibody for solid phase (microtiter wells) immobilization and another monoclonal antibody in the solutions. The third antibody which recognize the second antibody conjugated with an enzyme (horseradish peroxidase). In the assay procedure, standards and test specimen (serum) are added to the 25-OH Vitamin D antibody coated microtiter wells, incubation 30 minutes together with the second antibody. After wash, the third antibody labeled with horseradish peroxidase (conjugate) is added. If human 25-OH Vitamin D is present in the specimen, it will combine with the antibody on the well and the enzyme conjugate resulting in forming sandwiches between the solid phase and enzyme-linked antibodies. After incubation, the wells are washed with water to remove unbound labeled antibodies. A solution of TMB is added and incubated for 20 minutes, resulting in the development of a blue color. The color development is stopped with the addition of Stop Solution.The color is changed to yellow and measured spectrophotometrically at 450 nm. The concentrations of Vitamin D is directly proportional to the color intensity of the test sample.

REAGENTSSUPPLIED

Coated Microplate: 1 plate (8×12 wells), Ready to use. Monoclonal anti- 25-OH vitamin D-antibody coated microtiter plate and sealed in an aluminum bag. Remove the strips in the resealable bag with a desiccant to protect from moisture after opened. Store at 2~8℃until expiration date.

HRP Conjugate: 1 vial of 22ml, Ready to use. Store at 2~8℃ until expiration date.

Calibrator: 6 vials of 0.2ml. Labeled with S0 to S5 and the concentration of PRL is 0, 10, 20, 50,100, 150 ng/ml. Store at 2~8℃ until expiration date.

Control: 2 vials of 0.2ml.

Vitamin D Sample Diluent:1 vial of 22 ml, Ready to use. Store at 2~8℃ until expiration date.

TMB Substrate : 1 vial of 12 ml, Ready to use. Store at 2~8℃ until expiration date.

Stop Solution: 1 vial of 12 ml, Ready to use. Store at 2~8℃ until expiration date.

Wash buffer: 1 vial of 15ml, Concentrate 50-fold, diluting with deionized water before the assay. Store at 2~8℃ until expiration date.

Plate sealer: 2 pieces.

Plastic resealable bag: 1 set.

Instruction manual: 1 copy.

PREPARATIONS

1.  Allow all specimens and reagents to reach room temperature (~25°C) and mix thoroughly by gentle inversion before use.

2.Prepare Wash Buffer by diluting Wash Concentrate 20-fold with deionized water. The diluted wash solution is stable in room temperature for at least one week.

PRECAUTION FOR USERS

1. Handling should preclude any pipetting by mouth. Use only pipettes with disposable tips for each specimen.

2.Do not mix materials from different master lots. Do not use kit components beyond the expiration date.

3.All materials should be brought to room temperature before use.