From the Guidelines
Hyperlipidemia is classified into primary and secondary types, with primary hyperlipidemias further divided into five main types based on the elevated lipid levels, including Type I (familial chylomicronemia), Type II (familial hypercholesterolemia and familial combined hyperlipidemia), Type III (dysbetalipoproteinemia), Type IV (hypertriglyceridemia), and Type V, which combines features of Types I and IV. The classification of hyperlipidemia is crucial for determining the appropriate treatment approach, which may involve lifestyle modifications and medications such as statins, fibrates, bile acid sequestrants, or PCSK9 inhibitors, depending on the specific type of hyperlipidemia and cardiovascular risk factors 1.
Primary Hyperlipidemias
Primary hyperlipidemias are caused by genetic factors and include:
- Type I (familial chylomicronemia): elevated chylomicrons and triglycerides due to lipoprotein lipase deficiency
- Type II: divided into IIa (familial hypercholesterolemia), characterized by elevated LDL cholesterol, and IIb (familial combined hyperlipidemia), which shows increases in both LDL and VLDL
- Type III (dysbetalipoproteinemia): features elevated IDL particles
- Type IV (hypertriglyceridemia): involves increased VLDL and triglycerides
- Type V: combines features of Types I and IV with elevations in chylomicrons, VLDL, and triglycerides
Secondary Hyperlipidemias
Secondary hyperlipidemias result from underlying conditions like diabetes, hypothyroidism, kidney disease, or medication side effects, and can be managed by addressing the underlying cause and implementing lifestyle modifications and medications as needed 1.
Importance of Classification
Understanding the classification of hyperlipidemia is essential for proper treatment and management, as different types of hyperlipidemia require different approaches to reduce cardiovascular risk and improve patient outcomes 1.
From the FDA Drug Label
Gemfibrozil Tablets, USP are indicated as adjunctive therapy to diet for: 1. Treatment of adult patients with very high elevations of serum triglyceride levels (Types IV and V hyperlipidemia) Drug therapy is not indicated for patients with Type I hyperlipoproteinemia, who have elevations of chylomicrons and plasma triglycerides, but who have normal levels of very low density lipoprotein (VLDL). Reducing the risk of developing coronary heart disease only in Type IIb patients without history of or symptoms of existing coronary heart disease
The different types of hyperlipidemia mentioned are:
- Type I hyperlipoproteinemia: characterized by elevations of chylomicrons and plasma triglycerides, but with normal levels of very low density lipoprotein (VLDL)
- Type IV hyperlipidemia: characterized by very high elevations of serum triglyceride levels
- Type V hyperlipidemia: characterized by very high elevations of serum triglyceride levels, with elevations of VLDL-cholesterol as well as fasting chylomicrons
- Type IIa: characterized by elevations of LDL-cholesterol only
- Type IIb: characterized by a triad of lipid abnormalities: low HDL-cholesterol levels in addition to elevated LDL-cholesterol and elevated triglycerides 2
From the Research
Types of Hyperlipidemia
- Hypercholesterolemia: characterized by high levels of cholesterol in the blood 3
- Hypertriglyceridemia: characterized by high levels of triglycerides in the blood 3
- Mixed hyperlipidemia: characterized by high levels of both cholesterol and triglycerides in the blood 3
- Familial combined hyperlipidemia (FCHL): a genetic disorder characterized by at least two different forms of lipid abnormalities, including hypercholesterolemia and hypertriglyceridemia 4
- Combined hyperlipidemia (CHL): a common disorder defined by concurrently elevated low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) levels 5
- Isolated hypercholesterolemia: characterized by high levels of LDL-C in the blood 5
- Isolated hypertriglyceridemia (HTG): characterized by high levels of TG in the blood 5
Classification of Hyperlipidemia
- Based on lipoprotein analyses by electrophoresis and ultracentrifugation 6
- Based on the presence of hypercholesterolemia, hypertriglyceridemia, or mixed hyperlipidemia 3
- Based on the genetic background of patients, including the presence of rare variants or polygenic scores for elevated LDL-C or TG 5
Diagnosis and Treatment of Hyperlipidemia
- Diagnosis based on lipid levels, including cholesterol, triglycerides, LDL-C, and HDL-C 3
- Treatment options include statins, bile acid sequestrants, ezetimibe, and proprotein convertase subtilisin/kexin type 9 (PCSK9) enzyme inhibitors 7
- Targeted treatment is ideal, but necessitates identification of the genetic background of patients 4