Analytical evaluation and clinical application of insulin and C-peptide by a whole blood, lateral flow, point of care (POC) assay system

Abstract

The analytical performance and clinical application of measuring insulin and connecting peptide (C-peptide) by point of care (POC) assay were evaluated. A POC assay system (SelexOn, Osang Healthcare Inc., Anyang-si, Korea) was evaluated for precision, linearity, limit of blank (LOB), and limit of detection (LOD). Method comparison was performed with the Cobas Elecsys insulin and C-peptide assay (Roche Diagnostics GmbH, Mannheim, Germany) using 215 and 201 patient specimens for insulin and C-peptide, respectively. For clinical application, insulin resistance indices were studied. Homeostasis model assessment (HOMA) 1 and 2, Quantitative insulin sensitivity check index (QUIKI), fasting insulin resistance index (FIRI), and other indices were evaluated. The coefficient of variation (CV) of imprecision for low, medium, and high concentrations was 10.8%1, 15.99%, and 12.05%, respectively, for insulin and 9.21%, 13.51%, and 13.77%, respectively, for C-peptide. The linearity was validated to 839.78 pmol/L for insulin and to 17.30 nmol/L for C-peptide. LOB and LOD were 8.05 and 9.72 pmol/L for insulin and 0.05 and 0.08 nmol/L for C-peptide, respectively. For the method comparison, the regression equation was y ¼ 1.259x À 8.818 (r ¼ 0.957) for insulin and y ¼ 1.163x-0.088 (r ¼ 0.985) for C-peptide. The ROC value and overall accuracy were as follows:

Procalcitonin as a prognostic marker for sepsis based on SEPSIS‐3

“…Fluorescent immunoassay was used and the diagnostic precision was analyzed for 20 working days, and duplicated runs were measured two times within the working day (2 × 2 × 20 protocol) and coefficient of variation (CV) was calculated. The CV of low level (1.089 ng/mL) and high level material (11.69 ng/mL) was as follows: repeatability, 6.51%, 5.65%; between‐run, 9.73%, 8.12%; between‐day, 8.08%, 7.27%; within‐laboratory, 14.2%, 12.3%, respectively (Table ) . The limit of blank and limit of detection provided by the manufacturer were 0.044 and 0.066 ng/mL.…”

Lateral flow assays for hormone detection

“…In particular, the long-term plan for diabetes is to develop digital self-management support tools. 142 The commercialisation of insulin LFAs, 48 and potential linking to a smartphone-readout system, would help to meet these targets and therefore reduce the burden of diabetes on the NHS and worldwide, due to earlier detection of complications in patients through continuous simple monitoring. Furthermore, much research exists into LFAs for fertility and stress hormones.…”

“…Recently, an LFA was described for the measurement of insulin and C-peptide for use in evaluating insulin resistance indices among diabetic patients. The SelexOn 48 system by Osang Healthcare Inc. comprised a cartridge which detected the analytes in a sandwich immunoassay using capture antibodies conjugated with gold nanoparticles. The device contained a camera which detected the intensity of the gold nanoparticles allowing for densitometric analysis.…”

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“…Target value (range) of Level 1 (QNPS‐112) and Level 2 (QNPS‐212) was as follows: 315 pg/mL (252–378); 1034 pg/mL (827–1241), respectively. Repeatability, between‐run, between day, and within‐ laboratory coefficient of variation (CV) was analyzed 15 …”