Exploring socio-economic, biochemical, and genetic factors influencing thyroid status in Indian school-going adolescents.

Thyroid hormones are central to regulating metabolism, growth, and development, yet their complex interactions with socioeconomic, metabolic, and genetic factors remain understudied in diverse populations. We compared thyroid profiles - free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) in Indian adolescents with anthropometric traits, metabolic markers, and socioeconomic status (SES). We observed that adolescents from higher SES backgrounds exhibited greater metabolic dysregulation, altered thyroid profiles, and abnormalities in lipid and adipokine levels. Subclinical (16.1%) and clinical hypothyroidism (1.1%) were found to be prevalent in this population but were not associated with obesity. Instead, they showed links with dyslipidemia and altered adipokine profiles. To investigate the genetic basis of thyroid traits, we conducted an exome-wide association study (ExWAS, N = 4324), and a two-staged genome-wide association study (GWAS, N = 4854). The ExWAS revealed two novel loci for TSH (GYS2 and CEP162) and fifteen novel loci for FT4, including ZNF467, P3H3, CRLF3, SPATA2L, MEFV, THNSL2, COL27A1, COL28A1, IGSF3, ZNF732, MOG, GABBR1, HPF1, LOC440563, and SPEG. The GWAS identified novel associations at near-genome-wide significance for TSH (ACTL7B) and FT4 (LINC00648, YTHDC1, and C2CD4B). We also replicated established associations in FOXE1 and IGFBP5. Our findings suggest that SES, metabolic health, and genetics jointly influence thyroid function in Indian adolescents. The identification of population-specific loci emphasizes the importance of ancestry-informed genetic studies and supports the development of precision interventions to enhance pediatric thyroid health.