Hyperlipidemia is an elevation of lipids (fats) in the bloodstream. These lipids include cholesterol, cholesterol esters (compounds), phospholipids and triglycerides. They're transported in the blood as part of large molecules called lipoproteins. These are the five major families of blood (plasma) lipoproteins: chylomicrons very low-density lipoproteins (VLDL) intermediate-density lipoproteins (IDL) low-density lipoproteins (LDL) high-density lipoproteins (HDL)
When hyperlipidemia is defined in terms of a class or classes of elevated lipoproteins in the blood, the term hyperlipoproteinemia is used. Hypercholesterolemia is the term for high cholesterol levels in the blood. Hypertriglyceridemia refers to high triglyceride levels in the blood.
Common secondary causes of hypercholesterolemia (specifically, high LDL cholesterol) include hypothyroidism (that is, low thyroid hormone levels), pregnancy, and kidney failure. Common secondary causes of hypertriglyceridemia include diabetes, excess alcohol intake, obesity, and certain prescription medications (such as glucocorticoids and estrogen). Hyperlipidemia, along with diabetes, hypertension (high blood pressure), positive family history, and smoking are all major risk factors for coronary heart disease.