What is lp(a) in blood test?

A friend of mine was tested for Lp(a). What is that? 

This is a relatively new blood test. Lp(a), which stands for “lipoprotein small a,” is a material produced by the liver that increases the tendency of the blood to clot. A higher Lp(a) level increases the risk of a heart attack. It is primarily determined by inheritance and usually can’t be raised or lowered through diet or by most medicines. Premenopausal women have lower levels of Lp(a) than postmenopausal women, because of the presence of circulating estrogen. If your Lp(a) level is elevated, your doctor will take that into consideration and work harder to lower your other risk factors.