Given that serum FGF21 levels are more prone to be decreased under the status of hypothyroidism as described above, it could be proposed that that the thyroid-stimulating hormone could induce FGF21 gene expression though ANGPTL6 whereas the thyroid hormones might have opposite effect on modulating serum concentrations of FGF21 compared with thyroid-stimulating hormone. Here, FGF21 is linked to hypothyroidism.