Atherosclerosis in uremia: possible roles of hyperparathyroidism and intermediate density lipoprotein accumulation

Cardiovascular motality is high in patients with chronic renal failure treated with dialysis, and secondary hyperparathyroidism may promote atherosclerogenesis. Recent studies have revealed advanced atherosclerosis in hemodialysis patients by using high-resolution B-mode ultrasonography. Multiple regression analyses indicated that hyperphosphatemia and hyperparathyroidism were associated with increased intima-media thickness (IMT) of the carotid and femoral arteries in hemodialysis patients, respectively. Hypocalcemia and hyperparathyroidism independently and adversely affect the lipoprotein profile by suppressing hepatic triglyceride lipase (HTGL), a lipid-regulating enzyme playing important roles in the metabolism of intermediate density lipoprotein (IDL) and high density lipoprotein (HDL). Plasma IDL is raised markedly, and HDL is lowered in uremia. These lipoprotein changes are closely associated with increased aortic pulse wave velocity (PWV), an index of aortic sclerosis. These findings support the hypothesis that deranged calcium-phosphate homeostasis and secondary hyperparathyroidism promote atherosclerosis in uremia, at least partly by affecting lipoprotein metabolism. Adequate dialysis and efforts to normalize calcium, phosphate and PTH would be beneficial in preventing not only bone disease, but atherosclerosis as well.