Quantification of oxalate by novel LC-MS/MS: assay development, validation and application in lumasiran clinical trials.

A novel assay to measure plasma oxalate was developed and validated successfully in accordance with regulatory guidelines. The required sample volume was only 100 µl of plasma, which is especially favorable in the pediatric population, and there is no need to acidify blood at the collection site before processing. The assay accurately determines plasma oxalate levels, which were used as a measure of efficacy in the lumasiran clinical trials.