What are the normal levels and explanations of total cholesterol, HDL (High-Density Lipoprotein) cholesterol, and LDL (Low-Density Lipoprotein) cholesterol?

Understanding Cholesterol: Total, HDL, and LDL

What These Numbers Mean

Cholesterol is transported in your blood by three main lipoproteins—total cholesterol (the sum of all cholesterol), LDL cholesterol (the "bad" cholesterol that builds up in arteries), and HDL cholesterol (the "good" cholesterol that removes cholesterol from arteries)—and understanding their normal ranges is essential for cardiovascular risk assessment. 1, 2

Total Cholesterol

Total cholesterol represents the sum of all cholesterol-carrying particles in your blood, including LDL, HDL, and other lipoproteins. 3

Normal and Target Levels:

• Desirable: <200 mg/dL (5.2 mmol/L) for general population screening 4
• Borderline-high: 200-239 mg/dL 4
• High: ≥240 mg/dL (6.2 mmol/L) 2, 4
• Primary prevention goal: <190 mg/dL (5 mmol/L) for asymptomatic individuals 1
• High-risk/secondary prevention goal: <175 mg/dL (4.5 mmol/L) 1

LDL Cholesterol (Low-Density Lipoprotein)

LDL cholesterol is the primary target for treatment because nearly all lipid-lowering trials have demonstrated that LDL reduction directly improves cardiovascular outcomes, with every 40 mg/dL reduction producing dose-dependent reductions in cardiovascular disease. 5, 6

Normal and Target Levels:

• Optimal physiologic range: 50-70 mg/dL (the level seen in hunter-gatherers, human neonates, and wild mammals who don't develop atherosclerosis) 7
• Optimal clinical target: <100 mg/dL (2.6 mmol/L) 2, 8
• Borderline: 130-159 mg/dL 4
• High: ≥160 mg/dL (4.1 mmol/L) in adults without other risk factors 2, 8
• High with risk factors: ≥130 mg/dL (3.4 mmol/L) when two or more cardiovascular risk factors are present 2

Risk-Based Treatment Targets:

• Very high-risk patients (established cardiovascular disease): <70 mg/dL or at least 50% reduction from baseline 3, 1
• High-risk patients (10-year cardiovascular death risk ≥5%): <100 mg/dL (2.5 mmol/L) 1
• Moderate-risk patients: <130 mg/dL 5
• Lower-risk patients: <160 mg/dL 5

HDL Cholesterol (High-Density Lipoprotein)

HDL cholesterol is the "protective" cholesterol that removes cholesterol from arteries and transports it back to the liver. Higher levels are associated with lower cardiovascular risk, with HDL inversely associated with cardiovascular mortality. 5, 6

Normal and Target Levels:

• Low (increased risk) in men: <40 mg/dL (1.0 mmol/L) 3, 2, 8
• Low (increased risk) in women: <45-46 mg/dL (1.2 mmol/L) 1, 2
• Desirable target: >40 mg/dL in men, >45 mg/dL in women 2

Critical caveat: While low HDL indicates increased risk, the European Society of Cardiology explicitly states that no specific treatment goals are defined for HDL cholesterol—it should be used as a marker of increased risk rather than as a therapeutic target. 1, 5

The Total Cholesterol/HDL Ratio

The total cholesterol/HDL ratio combines atherogenic lipoproteins with protective HDL into a single risk marker, making it clinically useful for cardiovascular risk stratification, particularly in women and patients with diabetes or metabolic syndrome. 1

However, this ratio should be used for risk assessment only, not as a treatment target—focus therapeutic interventions on absolute LDL cholesterol goals based on cardiovascular risk category. 1, 5

Critical Clinical Pitfalls to Avoid

Measurement Requirements:

• Triglyceride measurements require a 12-hour fast for accuracy, while total and HDL cholesterol can be measured non-fasting 2
• When abnormal values are detected, repeat testing and averaging two measurements is recommended before making definitive treatment decisions 2

Calculation Limitations:

• The Friedewald formula for calculating LDL cholesterol (LDL = Total cholesterol - HDL - Triglycerides/5) is only valid when triglycerides are <400 mg/dL 1, 2
• When triglycerides exceed 400 mg/dL, use direct LDL measurement or the Sampson-NIH2 equation (valid up to triglycerides of 800 mg/dL) 1

Risk Misclassification:

• With total cholesterol in the 200-239 mg/dL range, misclassification of cardiovascular risk occurs in 47% of subjects when only total cholesterol is considered without measuring HDL and LDL 9
• Therefore, obtain a complete fasting lipid profile (total cholesterol, LDL, HDL, and triglycerides) in all patients with total cholesterol ≥200 mg/dL or when total cholesterol ≥250 mg/dL on initial screening 1, 9

Treatment Approach Algorithm

1. Measure total cholesterol first for initial screening in asymptomatic individuals 1
2. If total cholesterol ≥200 mg/dL or ≥250 mg/dL, obtain complete fasting lipid profile including HDL, LDL, and triglycerides 1, 9
3. Calculate the total cholesterol/HDL ratio for additional risk stratification 1
4. Focus treatment on lowering LDL cholesterol to absolute targets based on cardiovascular risk category, not on achieving a specific ratio 1, 5
5. For patients with triglycerides ≥200 mg/dL, calculate non-HDL cholesterol (total cholesterol minus HDL) as a secondary treatment goal, with targets 30 mg/dL higher than the corresponding LDL target 3, 2