Measurement of Nutritional and Inflammatory Biomarkers in Dry Plasma Spots (DPS) (P10-097-19)

Abstract

ObjectivesConduct time and temperature stability experiments on Nutritional Biomarkers (NBs) and inflammation markers extracted from ViveBio Dry Plasma Spots (DPS). MethodsBlood samples of 3 hematocrits (20, 30 and 45%) were created by combining purchased red blood cells (RBC) and sera. Blood samples of 35 μL were loaded onto ViveBio plasma separators. The underlying pads with plasma were stored at 45°, 23°, 4°, -20° and -70°C. Samples were tested on days 0, 1, 3, 7, 14, 28, 84 and 168.Ferritin, Retinol Binding Protein (RBP4), soluble Transferrin Receptors (sTfR), Thyroglobulin (Tg), α-acid Glycoprotein (AGP), and C-Reactive Protein (CRP) were measured using the Quansys Biosciences, Q-Plex Micronutrient Array (Q-Plex). Values measured in the liquid sera were used as reference values for the DPS.Red blood cell (RBC) folates and serum vitamin B12 were measured using a 96 well plate microbiological assay (ALPCO-Immundiagnostik AG).25OH-Vitamin D3, Retinol, Methylmalonic acid (MMA) and Homocysteine (HCY) were measured using LC-MS/MS.The Q-Plex was compared at 3 independent laboratories using a group of 80 whole blood samples, non-spiked and spiked with AGP, CRP, HRP2 and sTfR. Liquid plasma and extracted plasma from ViveBio pads were generated and stored at -80°C four weeks prior to assay. ResultsOverall, the measured values for Ferritin, RBP4, Tg, AGP, CRP, 25OH-D, Retinol and MMA decrease with increasing storage temperature and length of storage. Ferritin and Tg exhibited the best stability at 16.8% and 8.0% over a 6 month period. Vitamin B12 exhibited very poor stability declining to below the LOQ within day 3. Most of the NBs at 1 month correlated well with liquid plasma values (r2 = 0.42 to 0.99) (AGP at 23°C, r2 = 0.428; at -70°C r2 = 0.990 Ferritin stored at 23°C, r2 = 0.854; at -70°C r2 = 0.992; Thyroglobulin at 23°C, r2 = 0.916; at -70°C r2 = 0.830). ConclusionsWe have demonstrated that NBs can be analyzed in low volumes of DPS generated by the ViveBio plasma separator. The Q-Plex performed reproducibly on split samples among 3 labs. These tools offer great potential to improve nutritional assessment in population studies. Funding SourcesFunding provided by the Bill and Melinda Gates foundation.