Lipoprotein-X fifty years after its original discovery

•Lp-X is a lipoprotein rich in phospholipids and free cholesterol present in the plasma of patients during cholestasis.•Lp-X is formed by a bile lipoprotein moving to the blood vessels and catabolized by reticuloendothelial cells and the kidney.•Lp-X might be considered a defense mechanism against the toxic effect of free cholesterol in cholestasis.