Are you measuring serum or tissue levels? Are you measuring changes provoked by injury or injury severity related to Vit D metabolite levels pre-existing trauma?

Dear Greg,

We are going to measure serum level, and just to evaluate if there is association between the serum level and severity of the intestinal injury.

25(OH)D is more stable and is the accepted metabolite indicating Vit D sufficiency. It would be interesting to measure 1,25(OH)D levels prior to and post injury to see if serum 25(OH)D levels influence their levels. What we have found is that in certain conditions caused by occult and persistent infections, VDR becomes hypo responsive which can result in elevated serum 1,25(OH)D levels (above 110 pmol/L) and suppressed 25(OH)D levels due to down regulation of 25 hydroxylase. 

Is this a murine based study?

Thanks for your response. This study will be conducted in human patients.

Dear Ali

I agree with Greg, 25(OH)D is more stable and it is the usual form measured in serum to identify the level of VitD sufficiency. It could also be worthy to measure the serum levels of vitamin D binding protein.

Regards,

Bassem

If you do measure 1,25(OH)D, insure sample is kept cold and even frozen if there is a delay in conducting test post blood draw. 

The immuno modulatory effect is  1,25OH2 related, so it would make sense to measure 1,25 OH2. However, measuring 1,25OH2 gives you the blood / plasma level, when you want to know also the tissue level.

The mechanism of immunomodulatory effect of 1,25OH is clearly presented in a paper of van Etten and Mathieu in J Steroid Biochem Mol Biol 2005.

Another point to take into account:  the level of 1,25OH2 is maintained in a narrow range even over a wide range of 25OH concentrations, including severe deficiency.