Hi Marcos, you should do a stability test of a spiked sample in real matrix, then you are going to access the real need to colection tubes been ambar.

Thank you very much for the information. I plan to carry out a study of the stability of vitamin D and PTH to pre-analytical factors in blood samples collected from subjects with CKD in the hemodialysis central.

Hi Marcos, blood of plasma samples?

In addition to the EDTA tube, I intend to collect blood in tubes with protease inhibitor cocktail for measuring serum and plasma PTH. In Brazil does not have tubes protease inhibitors specific to measure PTH (EDTAK3 and Aprotinin). I got in contact with a representative of BD and I intend to experiment with the P800 collection system to stabilize blood plasma PTH. In it contains protease and esterase inhibitor cocktail as a stabilizer of Ghrelin and GLP1.

I think that is not necessary because 25OHD in serum is bound to DBP (D bindin protein).

Vitamin D ist stable in blood and serum for at least 3 days and is not light sensitive. In the refrigerator, Vit D is stable at least for 1 week (see Quality of Diagnostic Samples

Recommendations of the Working Group on Preanalytical Quality of the German United Society for Clinical Chemistry and Laboratory Medicine

stability of analytical samples in blood)

Parathyrin (PTH) is much more stable than unsually believed. In frozen state it is stable for 1 month, at 4°C for 1 day, at room temperature for 6 hours. As stabilizer, EDTA is sufficient. If you send me your email, I can give you the file containing all releveant data on stability of diagnostic from samples (from the WHO) including the cited literature.

Sighart Golf

Email: [email protected]

25OH vit D does not need protection from light. PTH is stable for about 6 hours. Be cautious what sample you use. We use serum as we have found that EDTA can interfere with the method on some platforms. This is negligable if the tube is full, but a half filled EDTA tube may have concentrations of EDTA that would interefere with some PTH methods.