What are the different types of lipid tests?

Types of Lipid Tests

The standard lipid profile for cardiovascular risk assessment should include total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides, which can be measured on fasting or non-fasting samples. 1

Standard Lipid Panel Components

• Total Cholesterol: Measures all cholesterol in the blood, including LDL, HDL, and other lipid components 1
• High-Density Lipoprotein (HDL) Cholesterol: Often called "good cholesterol" because it transports lipids back to the liver for recycling and disposal; high levels indicate a healthy cardiovascular system 1
• Low-Density Lipoprotein (LDL) Cholesterol: Often called "bad cholesterol"; high levels indicate surplus lipids in the blood, increasing cardiovascular risk 1
• Triglycerides: Derived from fats eaten in foods or from other energy sources; excess levels are independently associated with cardiovascular disease 1

Measurement Considerations

• Total cholesterol and HDL can be measured on non-fasting samples 1
• LDL cholesterol can be:
  • Calculated using the Friedewald equation when triglycerides are <300 mg/dL 1
  • Directly measured, which requires a fasting sample but is more expensive 1
• Abnormal results should be confirmed with repeated samples on separate occasions 1
• The average of multiple measurements should be used for risk assessment 1

Additional Lipid Measurements

• Non-HDL Cholesterol: Calculated as total cholesterol minus HDL cholesterol; includes all atherogenic lipoproteins including remnant cholesterol 1, 2
• Total Cholesterol/HDL Ratio: Better predictor of cardiovascular risk than total cholesterol alone 1
• LDL/HDL Ratio: Useful for risk classification but not reliable in cases of high triglycerides 3

Advanced Lipid Testing

Current guidelines do not recommend routine use of advanced lipid testing for cardiovascular risk assessment in asymptomatic adults 1:

• Apolipoprotein B (ApoB): Reflects LDL particle numbers; each LDL particle contains one molecule of ApoB 1
• Apolipoprotein A (ApoA): Related to HDL but with a less direct relationship 1
• Lipoprotein(a) [Lp(a)]: Should be measured at least once in patients at cardiovascular risk, particularly to explain poor response to statin treatment 4, 2
• LDL Particle Size and Density: Not recommended for routine cardiovascular risk assessment 1
• HDL Triglyceride and Oxidized HDL: Emerging biomarkers for assessing dysfunctional HDL 5

Clinical Application

• The standard fasting lipid profile is the primary panel for estimating risk of atherosclerotic cardiovascular disease 2
• LDL cholesterol is the primary target of lipid-lowering therapies 2
• Non-HDL cholesterol or apolipoprotein B should be used as secondary therapeutic targets in patients with mild-to-moderate hypertriglyceridemia (2-10 mmol/L or 175-880 mg/dL) 4, 2
• For on-treatment follow-up, LDL cholesterol should be measured or calculated by the same method to avoid errors in treatment decisions 2

Common Pitfalls

• Relying solely on total cholesterol can be misleading due to the different effects of LDL and HDL on health 1
• Using only LDL cholesterol for clinical decisions may miss residual cardiovascular risk, especially in patients with elevated triglycerides 2
• Failing to confirm abnormal results with repeat testing can lead to inappropriate treatment decisions 1
• Not accounting for non-fasting state when interpreting triglyceride levels 1