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

Öz

Objectives: Establishment of reference values by direct 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 triiodothyronine (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 selected from laboratory information system. Reference intervals were calculated by nonparametric methods Results: The following 95% reference intervals were determined: 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 indirect 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 nonparametric method may be confidently used to evaluate the reference 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.

Anahtar Kelimeler

• Direct method, indirect method, reference intervals, thyrotrophin, free thyroxine, free triiodothyronine.

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

Öz

Amaç: Referans bireylerden direkt yöntemle referans değerleri belirlemek her laboratuvar için hem zaman alıcı hem de maliyetli olmaktadır. Bu çalışmanın amacı, orta ve yaşlı populasyonun (yaş aralığı; 40-80 yaş) tirotropin (TSH), serbest tiroksin (ST4), serbest triiyodotironin (ST3) değerleri için Abbott Architect i2000 immunoassay analizöründe referans aralıklarını belirlemek ve indirekt ve direkt yöntem sonuçlarını birbiriyle karşılaştırmak. Yöntem: Direkt yöntem için referans bireyler (129 erkek, 131 kadın; yaş aralığı: 40-80) anket formuyla seçildi. İndirekt yöntem için TSH, ST4, ST3 ölçüm sonuçları laboratuar bilgi sisteminden [erkek n=(3060-3920), kadın n=(4090-4520) yaş aralığı:40-80 yıl] elde edildi. Referans aralıklar nonparametrik metod ile hesaplandı. Bulgular: %95 merkezi alan temel alınarak referans aralıkları belirlendi. Direkt yöntem grubunda; TSH, 0.32-4.38 µIU/mL; ST4, 0.75-1.32 ng/dL; ST3, 1.98-3.65 pg/mL idi. İndirekt yöntem grubunda; TSH, 0.29-4.36 µIU/mL; ST4, 0.71-1.37 ng/dL; ST3, 1.69-3.32 pg/mL idi. İndirekt yöntem grubu TSH ve ST4 için direkt yöntem grubuyla çok iyi bir uyum gösterdi. Sonuç: İndirekt yöntem ve nonparametrik metod Abbott Architect i2000 analizöründe TSH ve FT4 referans aralıkları belirlemede güvenli olarak kullanılabilir. Biz ilgilenilen bölgesel populasyonun referans aralıklarını belirlemek için indirekt yöntemle basit ve pratik bir yol öneriyoruz.

Anahtar Kelimeler

• Direkt yöntem, indirekt yöntem, referans aralık, tirotropin, serbest tiroksin, serbest triiyodotironin.

Kaynakça

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