What is considered hyperlipidemia?

What is Considered Hyperlipidemia?

Hyperlipidemia is defined as elevated fasting serum lipid levels, with triglyceride levels ≥150 mg/dL or LDL cholesterol levels exceeding target thresholds based on cardiovascular risk. 1

Triglyceride Classification

According to the Endocrine Society guidelines, hypertriglyceridemia is categorized as:

• Mild: 150-199 mg/dL (1.7-2.3 mmol/L)
• Moderate: 200-999 mg/dL (2.3-11.3 mmol/L)
• Severe: 1,000-1,999 mg/dL (11.3-22.6 mmol/L)
• Very severe: ≥2,000 mg/dL (≥22.6 mmol/L) 1

Mild to moderate hypertriglyceridemia increases cardiovascular disease risk, while severe and very severe levels significantly raise the risk of acute pancreatitis.

LDL Cholesterol Targets

LDL cholesterol targets vary based on cardiovascular risk:

• Very high-risk patients: <1.8 mmol/L (<70 mg/dL) or ≥50% reduction if target cannot be reached
• High-risk patients: <2.5 mmol/L (<100 mg/dL)
• Moderate-risk patients: <3.0 mmol/L (<115 mg/dL) 1

Metabolic Syndrome Criteria

Hyperlipidemia is a key component of metabolic syndrome, which is diagnosed when a person has 3 or more of these risk factors:

• Increased waist circumference (≥40 inches in men, ≥35 inches in women)
• High triglycerides (≥150 mg/dL) or taking medication for high triglycerides
• Low HDL-C (<40 mg/dL in men, <50 mg/dL in women) or taking medication for low HDL-C
• Elevated blood pressure (≥130/85 mm Hg) or taking antihypertensive medication
• Elevated fasting glucose (≥100 mg/dL) or taking medication to control blood sugar 1

Primary vs. Secondary Hyperlipidemia

Primary Causes

Primary hyperlipidemia includes genetic disorders such as:

• Familial hypertriglyceridemia
• Familial combined hyperlipidemia
• Familial dysbetalipoproteinemia 1

Familial hypercholesterolemia is characterized by total cholesterol >8 mmol/L (320 mg/dL) and LDL cholesterol >6 mmol/L (240 mg/dL). 1

Secondary Causes

Secondary causes of hyperlipidemia include:

• Lifestyle factors: Excessive alcohol intake, physical inactivity, diet rich in simple carbohydrates
• Medical conditions: Untreated diabetes, hypothyroidism, obesity, metabolic syndrome, renal or liver disease, pregnancy, autoimmune disorders
• Medications: Thiazides, beta blockers, estrogen, isotretinoin, corticosteroids, bile acid-binding resins, antiretroviral protease inhibitors, immunosuppressants, antipsychotics 1, 2

Clinical Implications

1. Cardiovascular Risk: Elevated triglycerides and LDL cholesterol increase the risk of atherosclerosis and cardiovascular disease 3

2. Pancreatitis Risk: Severe hypertriglyceridemia (>1,000 mg/dL) significantly increases the risk of acute pancreatitis 1, 4

3. Non-HDL Cholesterol: For patients with hypertriglyceridemia, non-HDL cholesterol (calculated by subtracting HDL from total cholesterol) is a better predictor of cardiovascular risk than LDL cholesterol alone 1

Common Pitfalls in Diagnosis

1. Fasting Status: Lipid levels should be measured after a 12-hour fast for accurate triglyceride assessment 1

2. Secondary Causes: Always evaluate for secondary causes of hyperlipidemia before initiating treatment 1

3. Risk Assessment: Don't rely solely on lipid levels; assess overall cardiovascular risk using multiple factors 1

4. Small LDL Particles: In patients with diabetes or metabolic syndrome, small dense LDL particles may be atherogenic even at normal LDL-C concentrations 1

5. Non-Fasting Samples: When triglycerides are elevated, calculated LDL may be inaccurate; consider using non-HDL cholesterol instead 1

By identifying and properly classifying hyperlipidemia, clinicians can implement appropriate treatment strategies to reduce cardiovascular risk and prevent complications like pancreatitis in patients with severe hypertriglyceridemia.