Absorption spectroscopy for the quantification of serum thyroglobulin and thyroglobulin antibody levels in differentiated thyroid carcinoma patients: A pilot study

Thyroglobulin (Tg) is a glycoprotein specifically synthesized by follicular thyroid epithelium. After thyroidectomy, serum Tg is a specific and sensitive marker for the presence of functioning thyroid tissue, and its measurement is fundamental in the follow-up of patients affected by differentiated thyroid carcinomas (DTCs). Serum antibodies against thyroglobulin (TgAbs) are common in patients with differentiated thyroid cancer (DTC) and can interfere in thyroglobulin (Tg) assays. Unfortunately, serum Tg measurement becomes useless in approximately 10-20% of DTC cases who are positive for anti-Tg antibodies that interfere with the Tg measurement. To overcome this problem, in the present study, we have used absorption spectroscopy technique for the quantification of Tg and TgAb. As a pilot study, current work was carried out on a limited number of 15 serum samples (5 normal and 10 DTC patients) and their absorption spectra were recorded in the UV-VIS region (200 nm-800 nm). Two peaks correspond to immunoglobulin antibody (IgG) were identified in the absorption spectrum of patient's serum sample and the areas/band sums (FWHM) of these two peaks were used to quantify the level of TgAb. The measured values of TgAb by enzyme-linked immunosorbent assay (ELISA) were matching well with the band sums of the IgG peaks proving the good sensitivity of the absorption technique.