Apolipoprotein B (APO B) is an essential protein, part of the very low density lipoprotein (VLDL) and low density lipoprotein (LDL). It helps provide structural integrity to complexes and directs transport of cholesterol and triglycerides to tissues. This test is used to help diagnose the cause of hyperlipidemia, especially when someone has elevated triglyceride levels, and to help determine an individual’s risk of developing atherosclerotic heart disease or coronary artery disease (CAD). HIGH levels of Apolipoprotein B could lead to the formation of plaques in artery walls and lead to hardening of blood vessels, hence increases the risk of heart attack. Increased levels are usually associated with diabetes, familial combined hyperlipidemia, hypothyroidism, and nephrotic syndrome. LOW levels are associated with cirrhosis, Abetalipoproteinemia, Reye syndrome, malnutrition, and hyperthyroidism. Measurement of Apolipoprotein A and B can reflect lipid metabolism disorders, since high levels of APO B with low levels of APOA1 constitute a strong risk factor for atherosclerosis. Other related tests: Apolipoprotein A, Serum.