Ann Lab Med.  2016 Sep;36(5):413-419. 10.3343/alm.2016.36.5.413.

Performance Evaluation of the Serum Thyroglobulin Assays With Immunochemiluminometric Assay and Immunoradiometric Assay for Differentiated Thyroid Cancer

• Cho YY
• Chun S
• Lee SY
• Chung JH
• Park HD
• Kim SW

• KMID: 2373570
• DOI: http://doi.org/10.3343/alm.2016.36.5.413

Abstract

BACKGROUND
Measurement of postoperative serum thyroglobulin (Tg) is important for detecting persistent or recurrent differentiated thyroid cancer. We evaluated the analytic performance of the DxI 800 assay (Beckman Coulter, USA) for serum Tg and anti-thyroglobulin antibodies (TgAbs) in comparison with that of the GAMMA-10 assay (Shinjin Medics Inc., Korea) for serum Tg and RIA-MAT 280 assay (Stratec, Germany) for TgAb.
METHODS
We prospectively collected blood samples from 99 patients thyroidectomized for thyroid cancer. The functional sensitivity was investigated in standards and human serum. Precision and linearity were evaluated according to the guidelines of the Clinical and Laboratory Standards Institute. The correlation between the two assays was assessed in samples with different Tg ranges.
RESULTS
The functional sensitivity of the DxI 800 assay for serum Tg was between 0.0313 and 0.0625 ng/mL. The total CV was 3.9-5.6% for serum Tg and 5.3-6.9% for serum TgAb. The coefficient of determination (R2) was 1.0 and 0.99 for serum Tg and TgAb, respectively. The cut-offs for serum TgAb were 4.0 IU/mL (DxI 800) and 60.0 IU/mL (RIA-MAT 280), and the overall agreement was 68.7%. The correlation between the two assays was excellent; the correlation coefficient was 0.99 and 0.88 for serum Tg and TgAb, respectively.
CONCLUSIONS
The DxI 800 is a sensitive assay for serum Tg and TgAb, and the results correlated well with those from the immunoradiometric assays (IRMA). This assay has several advantages over the IRMA and could be considered an alternative test for Tg measurement.

Keyword

DxI 800; Immunochemiluminometric assay; Evaluation; Performance; Thyroglobulin

MeSH Terms

Autoantibodies/*blood
Humans
Immunoradiometric Assay
Luminescent Measurements
Prospective Studies
Reagent Kits, Diagnostic
Reproducibility of Results
Thyroglobulin/*blood
Thyroid Neoplasms/*diagnosis/surgery
Autoantibodies
Reagent Kits, Diagnostic
Thyroglobulin

Figure

• 

  Fig. 1 Linearity profile of the DxI 800 assay for serum thyroglobulin (Tg) and anti-thyroglobulin antibody (TgAb). For the evaluation of linearity, five concentrations of control materials were used for both Tg and TgAb. The intended concentrations for serum Tg were 0, 94, 188, 282, 376, and 470 ng/mL (A), and 0, 480, 960, 1,440, 1,920, and 2,400 IU/mL for serum TgAb (B).

• 

  Fig. 2 Correlation of serum thyroglobulin (A) and anti-thyroglobulin antibody (B) concentrations measured by the two assays (results within analytical measurement ranges).

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