An addendum about Vitamin D testing: why you may need another Vitamin D test

With the advent of genetic testing (see the MTHFR page on STTM), some people have discovered they have a Vitamin D25 Receptor Mutation, known as VDR BSM.

The VDR gene encodes your vitamin D receptor. If you have a mutation of this gene, it can influence the density of your bone minerals in a negative way, causing increased risk of osteoporosis or bone fractures. It might even contribute to hyperparathyroidism or Rickets Type II.

Folks with this mutation convert vitamin D to vitamin D1,25, the active form of Vitamin D, but their Total Vitamin D 25 (the 25-hydroxy vitamin D) may be low because it’s converting to the Vitamin D1,25. Unfortunately, doctors aren’t checking the Vitamin D1,25 levels, which has a short half life, and they and you need to.

If you have too much of the active Vitamin D1,25, there is a possibility that the thyroid hormone T3 may not get to your cells well from being blocked thanks to the high D1,25. Says the website gettingstrong.org: “The excess 1,25-D can cause problems with other secosteroid receptors in the body, such as the thyroid receptor”. But we need more information to confirm this…so don’t take it as gospel yet!!

A high level of 1,25-dihydroxyvitamin D may occur when there is an excess parathyroid hormone or when there are diseases, such as sarcoidosis or some lymphomas, that can make 1,25-dihydroxyvitamin D outside of the kidneys.

Bottom line: it can be wise to check both D3 and D1,25.

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