Lipoprotein (a), or Lp(a), is a type of LDL cholesterol. Your Lp(a) level is determined by your genes and is not generally affected by lifestyle. Some research has shown that high levels of Lp(a) may be a sign of increased risk of heart disease. Your doctor might order an Lp(a) test if you already have heart disease but appear to have otherwise normal cholesterol levels. Lp(a) is often tested if you have a family history of early-onset heart disease or sudden death. It should also be tested if your LDL cholesterol doesn't respond well to drug treatment.