Multiplexed Micronutrient Array for Population Surveillance

Objective Deficiencies of vitamin A, iron and iodine affect a significant portion of the world's population and are often associated with adverse health outcomes, particularly among pregnant women and children. Efforts to characterize deficiency patterns have been hampered by a lack of measurement tools appropriate for large‐scale use. Since many of these micronutrients are not easily measured directly, reliable proxy biomarkers indicative of deficiency status have been identified and widely adopted. Inflammation or infection biomarker levels must also be measured, as inflammation affects the levels of vitamin A and iron status biomarkers. Furthermore, malaria infection is known to deplete iron levels, thus screening for malaria is also recommended. We previously developed a prototype multiplex immunoassay for the simultaneous measurement of five biomarkers relevant to assessing vitamin A, iron status and inflammation; retinol binding protein, soluble transferrin receptor, ferritin, alpha‐1‐acid glycoprotein and C‐reactive protein. Here we present an improved version of the immunoassay which has also been expanded to include measurement of the biomarkers for iodine deficiency (thyroglobulin) and malarial parasitemia (Histidine Rich Protein II). Method Using affordable technology from Quansys Biosciences, antibodies are coated in seven discrete regions of the well of a microtiter plate and the seven analytes are assayed in a single volume of sample. A control standard was developed for the assay that reflected the clinical range of each biomarker being assayed. Assay performance was evaluated by comparing multiplex and conventional assay results for plasma from 72 US volunteers. Results The new multiplex immunoassay and established conventional assay methods showed high correlation for all analytes tested (Average 0.77, p<.0001), improving on the values observed with the original 5‐plex plate. Use of a control standard specially designed for the multiplex assay in place of a commercially available standard allowed for more accurate quantitation of each analyte. The assay was also validated against the available WHO reference standards. Conclusions This 7‐plex micronutrient assay has excellent potential for use as a cost effective tool for population surveillance of vitamin A, iron and iodine deficiencies as well as malaria infectivity rates. Support or Funding Information This research is supported by the Bill and Melinda Gates Foundation.