HDL cholesterol
What it measures, and what changes the number.
HDL cholesterol measures the cholesterol carried in high density lipoprotein particles. These particles move cholesterol from tissues back toward the liver, and the test reports how much cholesterol they contain in the blood.
It is part of the standard lipid panel with Total cholesterol, LDL cholesterol and Triglycerides. It is also used to derive Non-HDL cholesterol and ratios such as the atherogenic index, and is sometimes read next to Apolipoprotein A1, the main protein of HDL particles.
HDL cholesterol changes relatively little after a meal, but because it is often ordered with triglycerides, many labs still request a fasting sample. Most labs use direct homogeneous assays, while older methods precipitate other lipoproteins first; the two approaches can give slightly different results, especially when triglycerides are elevated. Labs may print it as Colesterol HDL.
Often read alongside: Total cholesterol, LDL cholesterol, Triglycerides, Non-HDL cholesterol, Apolipoprotein A1