May 16, 2017 How to Tell the Difference Between Vitamin D and Calcium Deficiencies Vitamin D deficiency and calcium deficiency look very similar, and poorly interpreted blood tests can easily mislead us into taking the wrong supplements. Here’s how to tell them apart. How to watch it: Watch it on Facebook. Watch it on YouTube. How to share it and show it love: Share it on Facebook. Give it a thumbs up on YouTube. Like it on Instagram. Retweet it on Twitter.