Lipoprotein(a)

Lipoprotein(a), also written Lp(a), is a particle that travels in your blood. To make sense of it, start with its family: lipoproteins are particles made of protein and fat that carry cholesterol through the bloodstream to your cells. One type is LDL, short for low-density lipoprotein.

Here is how Lp(a) is put together. A special protein called apolipoprotein(a) is made mostly in the liver. It's a glycoprotein, which means a protein with sugars attached. That piece hooks onto a protein the LDL particle already carries, apolipoprotein B-100, through a type of chemical bond called a covalent link. Picture a truck that delivers cholesterol and has a trailer welded onto it: it's still the same truck, but now it hauls an extra part that doesn't come off.

Like any LDL, Lp(a) carries cholesterol through your arteries, the blood vessels that take oxygen-rich blood from your heart and lungs to the rest of your body. The difference is that its particles are stickier, and something sticky moving through a pipe gets stuck more easily. That's why they may be more likely to cause blockages and blood clots (clumps of blood) inside the arteries. How much Lp(a) you have is controlled by your genes, the instructions you inherit from your parents. Because your genes set that amount, diet and exercise may not change it. It's also settled early: by around age 5 you've reached your adult level, and from then on it seems to stay about the same.