Why is your Vit D low?

Active and stored vitamin D levels are measured using two different blood tests:
1. Stored Vitamin D (Vitamin D Status)
Active Vitamin D The test for the active form of vitamin D is called the 1,25-dihydroxyvitamin D test. Other names: 1,25(OH)\({}_{2}\)D, calcitriol.

Active to Stored Vit D should be 2:1. Active level of 45 ng/ml and Stored level of 21 ng/ml. These are optimal levels.