Are traditional reference ranges adequate for geriatric individuals? An indirect approach to thyroid testing
Turkish Journal of Biochemistry, cilt.51, sa.1, ss.7-14, 2026 (SCI-Expanded, Scopus, TRDizin)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 51 Sayı: 1
- Basım Tarihi: 2026
- Doi Numarası: 10.1515/tjb-2025-0424
- Dergi Adı: Turkish Journal of Biochemistry
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, EMBASE, Food Science & Technology Abstracts, Directory of Open Access Journals, TR DİZİN (ULAKBİM)
- Sayfa Sayıları: ss.7-14
- Anahtar Kelimeler: thyroid function tests, reference values, geriatrics, aging
- Sağlık Bilimleri Üniversitesi Adresli: Evet
Özet
Objectives: Physiological changes during aging may complicate the interpretation of thyroid function tests in elderly individuals. This study aimed to establish age- and sex-specific indirect reference intervals for thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) in individuals aged 65 years and older. Methods: Large-scale laboratory data collected between 2016 and 2025 were analyzed. Reference intervals were calculated using the refineR package with a Box-Cox transformation model and bootstrap resampling. Subgroup analyses were performed by age (65-74, 75-84, 85-96) and sex. Results: The upper limit of TSH decreased with advancing age, particularly in female, while FT3 levels showed a significant decline in older age groups. FT4 intervals remained relatively stable across age groups, though female exhibited higher upper limits compared to male. Conclusions: Manufacturer-provided adult reference intervals may be inadequate or less representative for the geriatric population. Implementing age- and sex-specific reference intervals in clinical practice will improve diagnostic accuracy and help prevent misdiagnosis and unnecessary treatment.