Apolipoprotein B (Apo B) is the major protein component of low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) particles, playing a crucial role in lipid transport and metabolism. This test measures Apo B levels to assess cardiovascular disease risk more accurately than traditional lipid measurements. Apo B represents the number of atherogenic lipoprotein particles, as each LDL and VLDL particle contains exactly one Apo B molecule. Elevated Apo B levels indicate increased numbers of these potentially harmful particles and are associated with higher cardiovascular disease risk. The test is particularly valuable for patients with metabolic syndrome, diabetes, or other conditions where traditional lipid measurements may not fully reflect cardiovascular risk. Apo B measurements help guide treatment decisions and monitor response to lipid-lowering therapy.