A complex of one or more lipids bound to one or more proteins. In humans, lipoproteins transport water-insoluble fats in the blood and are classified by their density: very-low-density lipoproteins (VLDLs), low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs). Cholesterol is carried through the bloodstream by lipoproteins. Healthwise, LDLs are known as "bad" cholesterol and HDLs are known as "good" cholesterol. When your doctor measures your cholesterol, he takes readings of the different types of cholesterol in your blood: LDL Cholesterol Desirable: less than 130 mg/dl Borderline High: 130-159 mg/dl High: more than 160 mg/dl HDL Cholesterol Desirable: more than 35 mg/dl Risk Level: less than 35 mg/dl