Direct versus indirect strategies for thyroid hormone reference intervals established in a middle-aged and elderly population on an immunoassay analyzer

摘要

Objectives:Establishment of reference values by di-rect strategy for selection of reference individuals is time-consuming and expensive for laboratories. The aim of this study was to establish reference intervals for thyrotrophin(TSH), free thyroxine (FT4), free triiodothyro-nine (FT3) in a middle-aged and elderly population (age range; 40-80 years) on an immunoassay analyzer using both direct and indirect strategies, and to compare the results of direct and indirect strategies. Materials and methods:As for direct sampling strategy, healthy reference individuals were randomly selected (129 male, 131 female; age range: 40-80) by questionnaire. As for indirect sampling strategy, the results of TSH, FT3, FT4 measurements of all individuals (male, n=3060-3920; female, n=4090-4520; age range 40-80 years), were se-lected from laboratory information system. Reference in-tervals were calculated by nonparametric methodsResults:The following 95% reference intervals were de-termined: For direct sampling group: TSH 0.32-4.38 μIU/mL; FT4 0.75-1.32 ng/dL; FT3 1.98-3.65 pg/mL. For indi-rect sampling group: TSH 0.29-4.36 μIU/mL; FT4 0.71-1.37 ng/dL; FT3 1.69-3.32 pg/mL. Indirect sampling group showed a good concordance in the reference intervals for TSH and FT4 with direct sampling group. Conclusion:Indirect sampling strategy and nonparamet-ric method may be confidently used to evaluate the refer-ence intervals of serum TSH and FT4 on an analyzer. We suggested the utilization of a very simple and practical way, indirect sampling strategy, for evaluating reference intervals for elderly population