Blood levels of Lp(a) are nearly completely determined by your genes, which means diet and lifestyle changes can't nudge the number much, if at all. According to some experts, high Lp(a) is the most common inherited risk factor for early heart disease. So why don't doctors routinely test for it? For one thing, the exact prevalence of elevated Lp(a) in the general population is unknown, although as many as 20% of people may have worrisomely high levels, according to the Lipoprotein(a) Foundation. Secondly, because of wide variations in Lp(a) testing procedures and standards, defining what constitutes a "high" level isn't entirely clear. In general, Lp(a) levels below 50 milligrams per deciliter (mg/dL) aren't considered especially high. People with triple-digit readings (100 mg/dL and higher) may have potentially aggressive heart disease. But the main reason widespread testing doesn't make sense is the lack of FDA-approved treatments proved to lower heart disease risk among people with high Lp(a). Injectable cholesterol-lowering drugs known as PCSK9 inhibitors such as evolocumab (Repatha) or alirocumab (Praluent) may lower Lp(a) by about 30%. But other research suggests that a far greater drop in Lp(a) levels may be required to prevent heart attacks and other serious events.