Influence of iodine on the reference interval of TSH and the optimal interval of TSH: results of a follow‐up study in areas with different iodine intakes

Abstract

Iodine nutrition is an important factor associated with TSH concentration even in the rigorously selected reference population. Baseline TSH of 1.0-1.9 mIU/l is an optimal interval with the lowest incidence of abnormal TSH in 5 years.

Usefulness of serum thyrotropin for risk prediction of differentiated thyroid cancers does not apply to microcarcinomas: results of 1,870 Chinese patients with thyroid nodules

“…Even excluding patients with high thyroid antibodies, serum TSH concentration is an independent risk factor of DTC, suggesting the increasing risk of DTC in patients with TSH in the upper end of normal or markedly elevated level is unlikely to be solely due to increased antithyroid antibody levels. This demonstrates the real association between TSH and malignancy, given the well known influence of anti-thyroid antibodies on TSH [21,22]. Moreover, our data show that higher TSH in patients with DTC occurs independent of age, which is also an important influencing factor on serum TSH levels.…”

“…The sensitivity of TSH assay was 0.01 mIU/L. The reference range, intra-assay and inter-assay coefficients of variation were 0.3-4.8 mIU/L [21], 4.9% and 5.2%, respectively, for TSH. Serum TPOAb exceeding a level of 50 KIU/L and/or TgAb exceeding a level of 40 KIU/L were considered as high serum autoantibody values [22].…”

“…Serum TSH values were broken down into subgroups as follows: ≤0.3 mIU/L, 0.3-1.0 mIU/L, 1.0-1.9 mIU/L, 1.9-4.8 mIU/L and >4.8 mIU/L, based on cutoff values predetermined in a previous population study (21), in which we have set up reference range (0.3-4.8 mIU/L) and optimal interval (1.0-1.9 mIU/L) for serum TSH in terms of the development of thyroid dysfunction in 5 years. Similar to the population at large, the distribution of patients loosely followed attempting to find more predictors and markers which can distinguish malignancy from benign nodules.…”

An epidemiological study of the serum thyrotropin reference range and factors that influence serum thyrotropin levels in iodine sufficient areas of China

“…The sensitivity of the TPOAb and TgAb measurements is 10 IU/L. Serum TPOAb exceeding a level of 50 IU/L and /or TgAb exceeding a level of 40 IU/L were considered as positive [2].…”

“…erence range should be narrower [1,2]. A large-scale epidemiological survey reported that "greater than 95% of healthy euthyroid subjects have a serum TSH concentration <2.5μIU/mL [3].…”