Original scientific paper

Serum thyroglobulin antibody levels within or near to the reference range may interfere with thyroglobulin measurement

Zoltan Locsei ; 1st Department of Medicine, Markusovszky Teaching Hospital of County Vas, Szombathely, Hungary
Istvan Szabolcs ; Semmelweis University and National Medical Centre, Budapest, Hungary
Karoly Racz ; 2nd Department of Medicine, Semmelweis University, Budapest, Hungary
Gabor L. Kovacs ; Institute of Diagnostics, University of Pécs, Pécs, Hungary; Institute of Laboratory Medicine, University of Pécs, Pécs, Hungar
Dora Horvath ; 1st Department of Medicine, Markusovszky Teaching Hospital of County Vas, Szombathely, Hungary
Erzsebet Toldy ; Central Laboratory, Markusovszky Teaching Hospital of County Vas, Szombathely, Hungary Practical Diagnostics Department, University of Pécs, Pécs, Hungary

Abstract

High concentration of thyroglobulin antibodies (TgAb) is a major limiting factor of thyroglobulin measurements in patients with differentiated thyroid cancer. We investigated whether thyroglobulin antibody added to serum samples could interfere with the thyroglobulin assay. Thyroglobulin levels in serum samples with different concentrations of thyroglobulin were measured by electrochemiluminescence immunoassay before and after the addition of increasing concentrations of thyroglobulin antibody using the secondary calibrator solution of the thyroglobulin assay kit containing sheep thyroglobulin antibody to reach thyroglobulin antibody levels within or near to the reference range. Thyroglobulin and thyroglobulin antibody concentrations were also measured in 134 serum samples from 27 patients after thyroid ablation. There was a strong negative association (slope = -1.179) between thyroglobulin antibody and thyroglobulin concentrations in samples with added thyroglobulin antibody (beta = -0.86; P < 0.001). Changes in thyroglobulin concentrations were described mathematically as loss of thyroglobulin% = -0.2408 x Ln(thyroglobulin antibody IU/ml) + 0.1944. Thyroglobulin concentrations were significantly lower than those calculated from experiments with added thyroglobulin antibody in 26/134 samples from patients after thyroid ablation. We conclude that if the same TgAb interference exists in the presence of naturally occurring human TgAb, our observation may prove to be useful during follow-up of patients with differentiated thyroid cancer. However, further studies are needed to explore the clinical relevance of thyroglobulin antibody levels within or near to the reference range in monitoring these patients.

Keywords

antibody interference; thyroglobulin; thyroglobulin antibodies; assay

Hrčak ID:

89405

URI

https://hrcak.srce.hr/89405

Publication date:

15.10.2012.

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