Background: There is evidence to suggest that thyroid hormone may affect circadian rhythm.
Aim: Investigate changes in peripheral blood expression of circadian clock genes and melatonin and vitamin D in Egyptian women with Hashimoto Thyroiditis (HT).
Methods: Case–control study included 240 females divided into two groups: (Control group): 120 euthyroid healthy females & (HT group): 120 females with HT. Serum thyroid hormones, antibodies, melatonin, (25(OH)D), ionized calcium, hemoglobin were measured, Determination of gene expression of the brain and muscle aryl hydrocarbon receptor nuclear translocator-like 1 (BMAL-1), Period 2 (PER2), nuclear factor kappa B (NF-κB), sirtuin 1 (SIRT1), Toll-like receptor 4 (TLR4), and tumor necrosis factor alpha (TNF-α) , which are associated with the circadian clock.
Results: Melatonin, vitamin D, ionized calcium, and hemoglobin were lower in the HT group. Expression of BMAL-1, PER2, and SIRT1 was downregulated , whereas that of NFKB, TLR4, and TNF-α was upregulated in the HT group.
Conclusion: Suggests associations between HT and circadian rhythm, as reflected in the downregulation of BMAL-1 and PER2 gene expression, inflammatory response, and oxidative stress. The significant decrease in serum melatonin levels in HT patients strongly suggests an association between melatonin pathway and HT.