National Health and Nutrition Examination Survey III thyroid-stimulating hormone (TSH)-thyroperoxidase antibody relationships demonstrate that TSH upper reference limits may be skewed by occult thyroid dysfunction.

Context: The setting of the TSH upper reference limit impacts the diagnosis of mild hypothyroidism and is currently controversial.

Objective: Our objective was to evaluate factors influencing the TSH reference range.

Design: Nonpregnant subjects aged 12 yr and older from National Health and Nutrition Examination Survey III were used to study the relationships between TSH, thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies in different ethnic groups.

Clinical impact of thyroglobulin (Tg) and Tg autoantibody method differences on the management of patients with differentiated thyroid carcinomas.

Context: Changes in thyroglobulin (Tg) and/or Tg antibody (TgAb) methods can disrupt the serial monitoring of differentiated thyroid carcinoma (DTC) patients.

Objective: This study compared Tg measurements made in TgAb-negative and TgAb-positive sera using four RIA and 10 immunometric assay (IMA) methods.

Design: TgAb detection using a panel of 12 direct methods was contrasted with four Tg recovery tests.

Serum thyroglobulin autoantibodies: prevalence, influence on serum thyroglobulin measurement, and prognostic significance in patients with differentiated thyroid carcinoma.

The prevalence of circulating thyroid autoantibodies (TgAb or antithyroid peroxidase) was increased nearly 3-fold in patients with differentiated thyroid cancers (DTC) compared with the general population (40% vs. 14%, respectively). Serum TgAb (with or without antithyroid peroxidase) was present in 25% of DTC patients and 10% of the general population.

Current status and performance goals for serum thyroglobulin assays.

Serum thyroglobulin (Tg) measurements are used as a tumor marker for monitoring patients with differentiated thyroid carcinoma. The clinical utility of six different Tg methods [RIA or immunometric assay (IMA)] currently used in Europe and the US was evaluated, with focus on methodologic standardization, sensitivity, interassay precision across the typical clinical monitoring interval (6 to 12 months), "hook" effects (IMA methods), and Tg autoantibody interference. The methods evaluated were: DYNOtest Tg (Henning), OptiQuant Tg (Kronus), SELco Tg (Medipan), Thyroglobulin IRMA (Pasteur), Nichols Chemiluminescent ICMA (Corning Nichols), and an RIA developed by us (USC Endocrine Services Laboratory).

Current status and performance goals for serum thyrotropin (TSH) assays.

Current medical needs dictate that laboratories offer thyrotropin (TSH) assays that can reliably measure low TSH concentrations--a prerequisite for using the more cost-effective TSH-centered strategy currently recommended by the American Thyroid Association. This study reviews the functional performance of the TSH immunometric assay methods currently used in clinical practice. Methodological differences between methods, the rationale for using the 20% interassay CV as the functional sensitivity limit for patient reports, and both TSH-related and non-TSH-related specificity problems are reviewed.