RESUMO
BACKGROUND: Thyroglobulin (Tg) is the primary biochemical marker used to monitor patients with differentiated thyroid cancer (DTC) for residual or recurrent disease after total thyroidectomy, as only normal or well-differentiated malignant thyroid cells produce Tg. Here, we evaluated the precision and functional sensitivity (FS) of a recently developed highly sensitive Tg (hsTg) electrochemiluminescent immunoassay (ECLIA) and compared it to that of the radioimmunoassay (RIA) method using pooled human serum with low levels of Tg. METHODS: For the ECLIA method, the Elecsys Tg II kit (Roche Diagnostics, Germany) was used with an E170 analyzer (Roche Diagnostics). For the RIA method, the Tg-plus-RIA kit (BRAHAMS, Germany) was used with a Cobra Quantum gamma counter (Packard Instrument Company, USA). The precision and limit of detection (LOD) were determined according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. FS was determined using a modification of the CLSI guideline. RESULTS: The total precision of the hsTg ECLIA and RIA methods was 9.6% and 48.2%, respectively. The manufacturer-reported LOD was verified by the hsTg ECLIA (0.04 ng/mL), but not by the RIA method (>0.08 ng/mL). The hsTg ECLIA showed better FS (0.04 ng/mL at a coefficient of variation [CV] of 10%) than the RIA method (0.37 ng/mL at a CV of 20%). CONCLUSIONS: Thus, the hsTg ECLIA performed better than the RIA method in terms of FS, which is extremely important for the early detection of residual or recurrent disease in DTC patients after total thyroidectomy. The excellent performance of the hsTg ECLIA could allow for clinical Tg measurement without thyroid-stimulating hormone stimulation, in contrast to the insufficient performance of the RIA method.
Assuntos
Humanos , Biomarcadores , Elapidae , Imunoensaio , Limite de Detecção , Métodos , Radioimunoensaio , Tireoglobulina , Glândula Tireoide , Neoplasias da Glândula Tireoide , Tireoidectomia , TireotropinaRESUMO
Limit of detection is one of most important indicators of methodological evaluation.In consideration of the misunderstanding and incorrect differentiating sensitivity and limit of detection by clinical laboratory , equipment and reagent manufacturers and journals of laboratory medicine , this article would show detailed analysis and comparison to figure out the proper use method.
RESUMO
Objective To evaluate the limit of blank (LoB),limit of detection (LoD),limit of quantitation(LoQ)and functional sensitivity (FS)of prealbumin (PA)detected by the Roche Modular P automatic biochemical analyzer.Methods According to the EP17A file of the American Clinical and Laboratory Standards Institute (CLSI),saline as the blank sample and a series of low con-centration samples were detected by the Roche Modular P automatic biochemical analyzer for determining LoB,LoD and LoQ.And FS was determined based on the domestic universal method .Results LoB of PA was 16.35 mg/L,LoD was 18.23 mg/L,LoQ was temporarily unable to evaluate and FS was 25.00 mg/L.The report scope and the report mode in clinic were affirmed by combi-ning with the low value of the reportable scope.Conclusion LoD of PA detected by the Roche Modular P automatic biochemical an-alyzer is established,which provides more valuable information for clinical diagnosis and treatment.Conducting the comparison of different evaluation methods determines the advantages and limitation of the practical application of different methods.
RESUMO
O autor apresenta evidências recentes da literatura que mostram que ensaios de tiroglobulina sérica (sTg) com maior sensibilidade funcional apresentam a mesma qualidade que a obtenção da sTg estimulada por rhTSH ou hipotiroidismo, no seguimento de pacientes com câncer diferenciado de tiróide (CDT). Desta forma, propõe modificar a prática recomendada pelas diretrizes de sociedades internacionais para o seguimento desses pacientes (desenvolvidas enquanto os ensaios disponíveis apresentavam sensibilidade de 1 ng/mL), substituindo-se a obtenção da sTg estimulada por rhTSH ou hipotiroidismo pelo acompanhamento dos pacientes na vigência da terapia com L-T4 com a medida da sTg desde que se empreguem técnicas com sensibilidade funcional da ordem de 0,1-0,2 ng/mL.
The author reviews the literature on the new assays for serum thyroglobulin (sTg) presenting lower functional sensitivity and demonstrates that its use, whilst the patients are taking L-T4, presents better results than sTg following TSH stimulation in the follow-up of patients with differentiated thyroid carcinoma. Therefore, he suggests a revision on the guidelines for the follow-up of these patients (developed when the available assays present a sensitivity of 1 ng/mL), proposing the use of sTg assays with functional sensitivity of 0.1-0.2 ng/mL with the patients on L-T4 treatment instead of sTg stimulated by TSH.