Lipoprotein(a), or Lp(a), is a type of lipoprotein particle in the blood that is similar to LDL (low-density lipoprotein) but includes an additional protein called apolipoprotein(a). Blood levels of Lp(a) are largely determined by genetics and tend to remain relatively stable throughout a person's life. This test measures the amount of Lp(a) in the blood. The test is used to assess an inherited risk factor for cardiovascular disease. Elevated Lp(a) levels are associated with a higher risk of conditions such as heart disease, stroke, and narrowing of the arteries. It may be ordered for people with a personal or family history of early heart disease, or when cardiovascular risk is not fully explained by standard cholesterol measurements.