25-OH vitamin D

Information

Bone metabolism is primarily determined by the activity of the osteoblasts (cells which make bone) and osteoclasts (cells that resorb bone). These activities in turn are influenced by hormones like Vitamin D, parathyroid hormone and calcitonin.

Vitamin D are a group of structurally related hydrophobic vitamins of which the most important physiologically, are

Vitamin D3 from animals
And Vitamin D2 from plants and fungi

Vitamin is converted into its active form by a two step hydroxylation process. First step takes place in liver where it is hydroxylated at 25th position to yield 25-OH vitamin D. The next hydroxylation takes place in the kidney at 1st position. This yields 1,25-dihydroxy vitamin D (the active form).

Most of the vitamin D (about 90 percent) is bound to vitamin D binding protein. Another 10 % is bound to albumin. Only about 1 percent of it is free. The free and albumin bound vitamin D are considered biologically active.

Diagnostic Guidelines

Diagnostics are based on the estimation of 25-OH vitamin D levels. This is because this form of vitamin D is responsible for most of the metabolites of vitamin D in the blood despite 1,25-dihydroxy vitamin D being the biologically active form. The levels are adequate predictors of vitamin D status. Vitamin D is deficient in rickets in children and osteomalacia, which are both characterized by decreased bone mineralization.

Combined estimation of levels of vitamin D, parathyroid hormone and calcitonin accurately relay whether bone disorders or diseases are present or not.

25-OH vitamin D products

For Research Use Only. Not For Use In Diagnostic Procedures.
The individual product regulatory statements may vary, please refer to the instructions for use for more information.

Method:

Parameter:

Substrate:

Species/ Antigen:

wdt_ID	Method	Parameter	Substrate	Species/ Antigen
635	ELISA	25-OH vitamin D	antibody-coated microplate wells	25-OH vitamin D (D2 and D3)
636	ELISA	intact PTH	antibody-coated microplate wells	recombinant human parathormone (1-84)
637	ELISA	calcitonin	antibody-coated microplate wells	synthetic human calcitonin
	Method	Parameter	Substrate	Species/ Antigen