title: Combined measurement of ferritin, soluble transferrin receptor, retinol binding protein, and C-reactive protein by an inexpensive, sensitive, and simple sandwich enzyme-linked immunosorbent assay technique.
abstract: The measurement of vitamin A (VA) and iron status is very important in the assessment of nutritional deficiencies. The objective of this research was to develop a sandwich ELISA technique for the simultaneous measurement of ferritin, soluble transferrin receptor, retinol binding protein, and C-reactive protein (CRP) as indicators for VA and iron status. The inclusion of CRP as marker of infection allows for more accurate interpretation of VA and iron status. This is accomplished in a 30-microL serum or plasma sample using an ELISA with different capture and detection antibodies and different dilutions of the sample. Commercially available clinical serum controls were used for calibration purposes. The developed assays were compared to commercially available traditional tests. Regression coefficients comparing both assays were better than 0.84 (P < 0.001). Using a limited sample set, the sandwich ELISA assay produced very similar specificity and sensitivity compared to traditional methods when common cutoff values were applied. Intra- and interassay variability was between 5 and 14% for all tests. The cost of the materials for all 5 measurements decreases to less than $1/sample if a large number of samples is analyzed. Due to the low cost, high throughput, and comparability to traditional tests, this procedure has several advantages for assessing VA and iron status in population surveys.
authors.affiliation: SEAMEO, Regional Center for Community Nutrition, University of Indonesia, Salemba Raya 6, Jakarta 10430, Indonesia. erhardtj@uni-hohenheim.de
authors.forename: Juergen G
authors.initials: JG
authors.lastname: Erhardt
authors.forename: John E
authors.initials: JE
authors.lastname: Estes
authors.forename: Christine M
authors.initials: CM
authors.lastname: Pfeiffer
authors.forename: Hans K
authors.initials: HK
authors.lastname: Biesalski
authors.forename: Neal E
authors.initials: NE
authors.lastname: Craft
mesh_terms: D002097:C-Reactive Protein / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay / Q000191:economics / Q000379:methods*; D005293:Ferritins / Q000032:analysis*; D006801:Humans; D000090463:Iron Deficiencies; D009752:Nutritional Status; D011786:Quality Control; D011990:Receptors, Transferrin / Q000032:analysis*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012177:Retinol-Binding Proteins / Q000032:analysis*; D054839:Retinol-Binding Proteins, Plasma; D012680:Sensitivity and Specificity; D012995:Solubility; D014802:Vitamin A Deficiency / Q000175:diagnosis
chemical_list: D011990:Receptors, Transferrin; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D002097:C-Reactive Protein; D005293:Ferritins