Notably, PDE8B exhibits distinct bidirectional regulatory features in hypothyroidism and hyperthyroidism: in hypothyroidism, its inhibition may elevate cAMP levels to promote thyroid hormone synthesis; in hyperthyroidism, overactive cAMP signaling may be exacerbated via the PDE10A/PDE8B complex, further disrupting hormone metabolism. Here, PDE8B is linked to hypothyroidism.