Introduction to Body Calcium and Vitamin D

Calcium

Calcium is a major constituent of bone and hence an important structural element in the body.

Plasma Calcium

The total plasma calcium concentration is around 2.15-2.55 mmol/L and consists of three fractions:-

1.    Protein bound: 40-45% mainly to albumin

2.    Ionised: 45-50%

3.    Complexed: 5-10% (as citrate, phosphates and bicarbonate)

Vitamin D

Vitamin D occurs in two forms:

1.  Cholecalciferol (vitamin D) which is formed in the skin by the action of ultraviolet light on the epidermal steroid compound 7-dehydrocholesterol

2.    Ergocalciferol (vitamin D2) derived from plant products and irradiated yeast and bread (usually added to foods)