Hyperlipidemia and hypothyroidism

Hypothyroidism is closely associated with increased serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG). The thyroid gland plays an important role in this process because thyroid hormones (THs) modulate cholesterol production, transformation and clearance. Although recent evidence suggests that thyroid-stimulating hormone (TSH) itself also participates in hyperlipidemia, the underlying mechanism remains unclear. Others demonstrated that the pathologic development of hypothyroidism-related hyperlipidemia was associated with down-regulated THs and up-regulated TSH in serum. This finding suggests a role for hypothyroidism in hyperlipidemia and potentially in related cardio-metabolic disease. Multiple newly identified modulatory biomarkers, such as proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein (ANGPTLs), and fibroblast growth factors (FGFs), might play a role in modulating the risk of hyperlipidemia induced by hypothyroidism. Moreover, hypothyroidism also contributes to the production of dysfunctional high-density lipoprotein (HDL) particles. In the present review, we examine the relationship between hypothyroidism with the risk and pathologic development of hyperlipidemia. We explore mechanisms by which hypothyroidism promotes hyperlipidemia in general and its contribution to cardio-metabolic disease specifically.