Vitamin D (D2 and D3) is a group of fat-soluble secosteroids that act as hormones.
Humans obtain vitamin D from 3 sources:
- Plants as Vitamin D2
- Animal products as Vitamin D3
- Synthesis in the skin from cholesterol after exposure to ultraviolet sun light as Vitamin D3
D2 and D3 measurement is the best indicator of patient’s vitamin D status.
Gold Standard for Vitamin D testing is High Performance Liquid Chromatography (HPLC) which offers faster and more reliable results than all other testing methods.
Biological Functions of Vitamin D:
The most important role of Vitamin D is the regulation of Calcium and Phosphorus levels, which are essential in maintaining healthy and strong bones. In addition, Vitamin D is an important immune regulator which protects the immune system from contracting a number of autoimmune diseases.
Accumulation of Vitamin D in the body:
Accumulated Vitamin D in human body is converted to 25-Hydroxyvitamin D3 by a specific enzyme, then transported to the Kidney where it is converted to 1, 25-Hydroxyvitamin D3, which is the most potent form of Vitamin D, hence, facilitating calcium absorption. The half life of 1, 25-Hydroxyvitamin D3 is very short in blood, comparing to 25-Hydroxyvitamin D2, D3. Therefore, measuring its concentration will not give a correct indication of Vitamin D level.
Low Vitamin D levels may increase the risk for:
- Heart Disease
- Immune Diseases(e.g. multiple sclerosis, systemic lupus erythematosus)
- Alzheimer’s Disease
- Parkinson’s Disease
- Epilepsy amongst many other Diseases