[Development of Rapid Assay of Transthyretin in Whole Blood]

Transthyretin (TTR), a rapid turnover protein with a half-life of 2 days, which is shorter than that of albumin, is considered to be a sensitive indicator of a patient's nutritional status. We have newly developed a rapid assay of TTR by immunochromatography (IC) using samples of whole blood as well as serum at volumes of 10 μL. The fundamental performance was evaluated using control sera. In addition, whole blood samples were measured by IC and the results were compared with measured levels of plasma samples by turbidimetry and those of sera by nephelometry. The limit of quantification was 8.3 mg/dL. The linearity was 8.7-35.4 mg/dL. The reproducibility was 6.1-8.6% coefficient of variation. Bilirubin, hemolysis, chyle, and rheumatoid factor did not influence the measured levels. An increase of 1% in hematocrit resulted in a decrease of 1% in the measured levels. The correlation between IC (y) and nephelometry (x) was determined to be y = 0.927x+2.62 (r = 0.935, n = 64). The newly developed IC showed good performance and it was suggested that IC would be useful for nutrition monitoring as point of care test.