Cholesterol Testing Explained: HDL, LDL, and Everything Else

When you get a cholesterol test, you're not just getting a single number. Your lipid panel reveals several different measurements, each telling part of the story about your cardiovascular health. Understanding what these numbers mean can help you have more informed conversations with your healthcare provider.

What Is Cholesterol?

Cholesterol is a waxy, fat-like substance found in every cell of your body. You need it to make hormones, vitamin D, and substances that help digest food. Your liver makes all the cholesterol you need, but you also get cholesterol from animal-based foods.

The challenge with cholesterol is that too much of certain types circulating in your blood can build up in artery walls, increasing your risk for heart disease and stroke. That's why testing and monitoring matter.

The Complete Lipid Panel

A standard lipid panel measures four key components. Understanding each one helps you see the complete picture of your cardiovascular risk.

Total Cholesterol

This is the sum of all cholesterol in your blood. While it provides a general snapshot, it's not the most informative number on its own because it doesn't distinguish between "good" and "bad" cholesterol.

General ranges:

• Desirable: Less than 200 mg/dL
• Borderline high: 200-239 mg/dL
• High: 240 mg/dL and above

LDL Cholesterol (Low-Density Lipoprotein)

Often called "bad" cholesterol, LDL carries cholesterol to your arteries where it can accumulate in artery walls. High LDL is a major risk factor for heart disease and stroke. This is typically the number your doctor focuses on most when assessing your cardiovascular risk and considering treatment.

General ranges:

• Optimal: Less than 100 mg/dL
• Near optimal: 100-129 mg/dL
• Borderline high: 130-159 mg/dL
• High: 160-189 mg/dL
• Very high: 190 mg/dL and above

However, your target LDL depends on your overall cardiovascular risk. People with heart disease, diabetes, or multiple risk factors may need LDL levels below 70 mg/dL.

HDL Cholesterol (High-Density Lipoprotein)

Known as "good" cholesterol, HDL helps remove cholesterol from your arteries and transport it back to your liver for disposal. Higher levels of HDL are generally protective against heart disease.

General ranges:

• Poor (increased risk): Less than 40 mg/dL for men, less than 50 mg/dL for women
• Better: 50-59 mg/dL
• Best: 60 mg/dL and above

Think of HDL as your cardiovascular cleanup crew, working to keep your arteries clear.

Triglycerides

These are the most common type of fat in your body. You get them from food, and your body also converts excess calories, alcohol, and sugar into triglycerides for storage. High triglyceride levels, especially combined with high LDL or low HDL, can increase heart disease risk.

General ranges:

• Normal: Less than 150 mg/dL
• Borderline high: 150-199 mg/dL
• High: 200-499 mg/dL
• Very high: 500 mg/dL and above

Understanding Ratios

Your doctor might also look at the ratio between your total cholesterol and HDL, or between LDL and HDL. These ratios can provide additional insight into your cardiovascular risk beyond the individual numbers.

The total cholesterol to HDL ratio is calculated by dividing your total cholesterol by your HDL. A ratio of 5:1 or lower is generally considered good, with 3.5:1 being ideal.

Fasting Requirements

The traditional recommendation has been to fast for 9-12 hours before a lipid panel, having nothing but water. Fasting provides the most accurate triglyceride measurement because eating can significantly raise triglyceride levels temporarily.

However, recent guidelines from some organizations suggest that non-fasting tests may be acceptable for some people. Non-fasting tests can be more convenient and may actually reflect your typical daily cholesterol levels more accurately.

Your healthcare provider will let you know whether you need to fast. If you do need to fast:

• Schedule your test for morning when possible
• Continue taking your regular medications unless told otherwise
• Drink water as needed
• Avoid alcohol for 24 hours before the test

What Affects Your Cholesterol?

Many factors influence your cholesterol levels, some within your control and others not:

Factors You Can't Control

• Genetics: Some people inherit genes that cause high cholesterol (familial hypercholesterolemia)
• Age and sex: Cholesterol typically rises with age; women's cholesterol often increases after menopause

Factors You Can Influence

• Diet: Saturated fats, trans fats, and dietary cholesterol can raise LDL; fiber can help lower it
• Weight: Being overweight tends to increase LDL and triglycerides while lowering HDL
• Physical activity: Regular exercise can raise HDL and lower triglycerides
• Smoking: Damages blood vessels and lowers HDL
• Alcohol: Moderate intake may raise HDL, but excessive drinking raises triglycerides

Beyond the Numbers: Your Overall Risk

While your cholesterol numbers are important, they're just one piece of your cardiovascular risk puzzle. Your doctor will also consider:

• Blood pressure
• Diabetes or prediabetes
• Smoking status
• Family history of early heart disease
• Age
• History of cardiovascular events

These factors combined help determine your overall 10-year risk of having a heart attack or stroke, which guides treatment decisions.

When to Get Tested

General screening recommendations vary by organization, but typical guidelines suggest:

• All adults should have their cholesterol checked at least once between ages 20-39 if they don't have risk factors
• Adults ages 40-75 should be screened every 4-6 years if they don't have cardiovascular disease
• More frequent testing is recommended if you have risk factors, abnormal results, or are taking cholesterol-lowering medication
• People with a family history of early heart disease or familial hypercholesterolemia may need earlier or more frequent testing

Interpreting Changes Over Time

Cholesterol levels can fluctuate. A single test provides a snapshot, but tracking trends over time is more meaningful. Small variations between tests are normal and can result from:

• Recent illness
• Changes in diet or exercise
• Weight changes
• Stress
• Laboratory variation
• Time since last meal (if not fasting)

This is why doctors typically look at patterns rather than making treatment decisions based on a single test result.

Advanced Testing

In some cases, your doctor might order additional lipid tests:

• Lipoprotein(a): A genetic variant of LDL that can increase heart disease risk
• Apolipoprotein B: Measures the number of LDL particles, which some consider more predictive than LDL cholesterol alone
• LDL particle size: Small, dense LDL particles may be more harmful than large, fluffy ones

These tests aren't routine but may be recommended if you have a strong family history of heart disease, early heart disease yourself, or if standard tests don't seem to match your cardiovascular risk.

Working With Your Results

When you receive your cholesterol results, don't just look at whether individual numbers fall within "normal" ranges. Consider:

• How your numbers compare to previous tests
• The relationship between your LDL, HDL, and triglycerides
• Your overall cardiovascular risk profile
• Whether lifestyle changes you've made are moving your numbers in the right direction

Come to your follow-up appointment prepared with questions about what your specific results mean for your health and what steps might help improve your numbers if needed.