Vitamin D helps regulate calcium in the body needed for good bone health. The body makes its own vitamin D through foods we eat and from sun exposure of the skin. Calcium is absorbed from the gastrointestinal tract but requires enough vitamin D to do so. The two chemicals are linked together very closely through hormone regulation.
The difference between insufficiency and deficiency is a matter of degree. Vitamin D insufficiency is defined as a blood level of 25-hydroxyvitamin-D (25 OHD) that falls below 32 ng/mL. 25 OHD is a chemical compound that must be present in the body in order for vitamin D to be made. It is called a precursor (comes before) chemical.
Vitamin D deficiency occurs when 25 OHD levels fall below 20 ng/mL. The levels for insufficiency and deficiency are actually determined by another factor — and that is the amount of 25 OHD needed to keep parathyroid levels in the normal range.
Without going into the complex physiology of the body to explain the interactions between the hormonal systems, suffice it to say that vitamin D levels and parathyroid function are intimately linked together.
A blood test is required to find out your own vitamin D status. Your physician, nurse practitioner, or physician’s assitant can order this test for you. The results will be used to guide you regarding any changes required in diet, sun exposure, or vitamin supplementation you may need.