Serum Thyroid-stimulating Hormone Assays Research Articles

Identification and characterization of an antibody-bound thyroid-stimulating hormone (TSH) with differential effects on various clinically available serum TSH assays

Identification and characterization of an antibody-bound thyroid-stimulating hormone (TSH) with differential effects on various clinically available serum TSH assays

Guidelines for management of thyroid cancer in adults: implications for clinical biochemistry.

The implementation of recently published guidelines for the management of thyroid cancer in adults should result in improved clinical outcomes for patients with this condition. A clinical biochemist should be part of the support team for the local multidisciplinary thyroid cancer management team. Serum thyroid-stimulating hormone assays should have a minimum detection limit of 0.10 mU/L or lower and good baseline security. The measurement of both thyroglobulin and calcitonin is challenging and clinical biochemists should have detailed knowledge of the performance characteristics and limitations of the assays that they report, including those referred to a specialist centre, in order to facilitate clinically valid decisions on patient management.

Prevalence of subclinical hypothyroidism in a population living in the Milan metropolitan area.

Subclinical hypothyroidism is a condition characterized by increased levels of thyroid-stimulating hormone (TSH) associated with normal levels of free triiodothyronine (FT3) and free thyroxine (FT4). The exact prevalence of this condition in Italy is not known. The aim of this study was to assess the presence of subclinical hypothyroidism in 1001 subjects living in the Milan area (age 17-89) and apparently free from thyroid pathology. This sample which had applied to a large laboratory centre (Centro Diagnostico Italiano, Milano) for a routine check-up was seen from April to July 1996. A serum TSH assay was performed using a highly sensitive immunoenzymatic method, while an FT3 and FT4 assay was performed by means of a radioimmunologic method using commercial kits. The prevalence of subclinical hypothyroidism in the total population proved to be 4.7% (95% CI-Confidence Interval: 3.4-6.0). Sex stratification showed a prevalence of 6.1% in females and 3.4% in males. Prevalence in patients up to 65 was 4.2%. This value increased up to 8.0% in subjects over 65. By combining these variables, in females >65 prevalence increased to 11.3%. Overall, symptoms typical of overt hypothyroidism were found in 58.3% of patients suffering from subclinical hypothyroidism and in 39.9% of healthy subjects (p<0.02). The results of this study show that there is a significant presence (about 5%) of subclinical hypothyroidism in this population and that its frequency is more than doubled in women over 65. Early treatment might reduce the progression to overt hypothyroidism. The benefits of such a procedure were recently suggested by a decision making modelling approach applied to the Italian environment.

Screening for Mild Thyroid Failure at the Periodic Health Examination

To estimate the cost-effectiveness of periodic screening for mild thyroid failure by measurement of serum thyroid stimulating hormone (TSH) concentration. Cost-utility analysis using a state-transition computer decision model that accounted for case finding, medical consequences of mild thyroid failure, and costs of care during 40 years of simulated follow-up. Periodic health examinations in offices of primary care physicians. Hypothetical cohorts of women and men screened every 5 years during the recommended periodic examination, beginning at age 35 years. Adding the serum TSH assay to total serum cholesterol screening was compared to cholesterol screening alone. Discounted quality-adjusted life years (QALYs) and direct medical costs from a societal perspective. The cost-effectiveness of screening 35-year-old patients with a serum TSH assay every 5 years was $9223 per QALY for women and $22595 per QALY for men. The cost-effectiveness became more favorable when age at first screening was increased for both sexes and was always more favorable for women than men. Reduced progression to overt hypothyroidism and relief of symptoms increased QALYs, but did not substantially reduce direct medical costs. Finding hypercholesterolemia induced by mild thyroid failure reduced direct medical costs, but did not substantially increase QALYs. The cost of a TSH assay and the importance to patients of symptoms associated with thyroid failure were the most influential factors in sensitivity analyses. The cost-effectiveness of screening for mild thyroid failure compares favorably with other generally accepted preventive medical practices. Physicians should consider measuring serum TSH concentration in patients aged 35 years and older undergoing routine periodic health examinations. The cost-effectiveness of screening is most favorable in elderly women.