Vitamin D deficiencies

摘要

Methods for determining the amount of vitamin D compounds in a sample are provided. The methods can employ LC-MS/MS techniques and optionally the use of deuterated internal standards. Methods for diagnosing vitamin D deficiencies are also provided.

主权项

1. A method of determining whether or not a mammalian subject has a vitamin D deficiency, comprising:
a) obtaining a biological sample from the mammalian subject; b) deriving a sample from the biological sample by removing interfering components from the biological sample; c) determining an amount of 25-hydroxyvitamin D2 simultaneously with an amount of 25-hydroxyvitamin D3 in a single sample derived from the mammalian subject's biological sample, wherein the determining comprises using a mass spectrometry technique to detect underivatized 25-hydroxyvitamin D2 and underivatized 25-hydroxyvitamin D3 in the single sample, wherein the mass spectrometry technique comprises a LC-MS/MS technique and wherein the LC-MS/MS technique comprises the use of a triple quadrupole instrument in Multiple Reaction Monitoring (MRM), positive-ion mode, and wherein the LC-MS/MS technique comprises a Q1 scan tuned to select, independently, precursor ions that correspond to the [M+H+] of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3; d) comparing the amount of total 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in the single sample with clinical reference values indicative of vitamin D deficiency; and e) determining whether or not the mammalian subject has a vitamin D deficiency based on the comparisons in step d).