A Preliminary Study on the Development of a Fluorescence Immunochromatographic Assay for the Rapid Quantification of the Thyroid Stimulating Hormone in Serum Sample

Jeong, Dong Seok; Kang, Sung Ha; Choi, Moon Gi; Choi, Eui Yul

Abstract

BACKGROUND
Since the first introduction of radioimmunoassay for the quantification of the thyroidstimulating hormone (TSH), more advanced analytical methods have been developed and used in laboratories. However, they are still inconvenient in that they require time-consuming procedures, special safety in handling isotopes, expensive equipment, and a highly qualified expert. METHODS: As an immunoassay system for the rapid measurement of TSH in serum, we have developed a new analytical system based on immunochromatographic assay with fluorescencelabeled anti-TSH monoclonal antibodies. The assay system is composed of a test strip housed within a cartridge and a laser-fluorescence scanner for quantification. The strip contains a sample pad, an absorption pad, and a nitrocellulose membrane where a captured antibody is immobilized and antigen-antibody reaction occurs. Fifty microL of serum was added to 50 microL of a detector solution and the mixture was loaded onto the well of the sample pad on the cartridge. After incubation for 12 min, the cartridge was quantified with the laser-fluorescence scanner. RESULTS: The calibration curve displayed linearity (R=0.95) at concentrations of 1-40 mIU/L. Intraand inter-assay imprecisions were determined to be CVs within 10%. Analytical recovery was 93.9% at 3 different concentrations and the detection limit was 0.868 mIU/L of TSH. The new assay system correlated well with an Abbott AxSYM for quantification of TSH (R=0.97, slope 0.94, N=20). CONCLUSIONS: The TSH measurement system developed in this study showed good reproducibility. However, our TSH quantification system needs some improvement to be used in the medical field because of its low analytical sensitivity. With enhanced performance in analytical sensitivity, introduction of a whole-blood type strip, and a more miniaturized fluorescence scanner, we expect the TSH analytical system to be used for point-of-care testing in the near future.