| | Conditions & Treatments | Cholesterol

Understanding Cholesterol: A Guide to Healthy Levels, Risk Assessment, and Management

Cholesterol is a waxy, fat-like substance essential for cell membranes, hormone synthesis, and bile acid production. While the body produces all it needs, dietary and genetic factors influence blood levels. Abnormal cholesterol is a major modifiable risk factor for atherosclerotic cardiovascular disease (ASCVD).

Lipoprotein Classes and Clinical Significance

Lipoprotein	Primary Lipid	Function	Clinical Role
Chylomicrons	Triglycerides (85-90%)	Dietary fat transport (intestine → tissues)	Postprandial; not measured fasting
VLDL	Triglycerides (55-65%)	Endogenous TG transport (liver → adipose)	Precursor to IDL/LDL; atherogenic remnants
IDL	TG + Cholesterol	Intermediate	Atherogenic remnant
LDL	Cholesterol (50%)	Cholesterol delivery to tissues	Primary atherogenic particle; main treatment target
HDL	Protein (50%), Phospholipid	Reverse cholesterol transport	Anti-atherogenic; higher = lower risk (but U-curve at very high levels)
Lp(a)	Cholesterol + Apo(a)	Genetic variant of LDL	Independent risk factor; thrombogenic, pro-inflammatory

Key Lipid Metrics and Targets (2018 ACC/AHA, 2019 ESC/EAS)

LDL-C: Primary target. Goals by risk: Very high risk <55 mg/dL (<1.4 mmol/L) + ≥50% reduction; High risk <70; Moderate <100; Low <116.
Non-HDL-C: Total cholesterol minus HDL-C (all atherogenic particles). Secondary target = LDL goal + 30 mg/dL.
ApoB: Particle count. Superior risk predictor. Goals: <80 (very high), <90 (high), <100 (moderate) mg/dL.
Triglycerides: <150 normal; 150-199 borderline; ≥200 high. Fasting preferred but non-fasting acceptable (cutpoints differ).
HDL-C: >40 men, >50 women desirable; >60 cardioprotective. Not a treatment target.
Lp(a): Measure once. >50 mg/dL (125 nmol/L) = high risk. No approved specific therapy yet.

Risk Assessment

ASCVD Risk Calculator (Pooled Cohort Equations): 10-year risk for ages 40-75. Guides statin intensity.
Statin Benefit Groups: Clinical ASCVD; LDL ≥190; Diabetes 40-75; Primary prevention 40-75 with risk ≥7.5% (or ≥5% with enhancers).
Risk Enhancers: Family history of premature ASCVD, high Lp(a), metabolic syndrome, CKD, inflammatory diseases, South Asian ancestry, preeclampsia, premature menopause, ABI <0.9.
Coronary Artery Calcium (CAC) Scoring: Refines decision in borderline/intermediate risk. CAC=0 → defer statin (except smokers, diabetes, FH). CAC ≥100 or ≥75th percentile → favor statin.

Management

Lifestyle (Foundation for All)

Diet: Mediterranean/DASH/plant-based; saturated fat <7% of calories, trans fat minimal, soluble fiber 5-10g, plant sterols 2g.
Exercise: 150 minutes moderate/week aerobic + 2× resistance training.
Weight: BMI 18.5-24.9; waist <40" men, <35" women.
No tobacco; limit alcohol.

Pharmacotherapy

Class	Agents	LDL-C Reduction	Key Indications
Statins (HMG-CoA reductase inhibitors)	Atorvastatin, rosuvastatin (high-intensity); simvastatin, pravastatin (moderate)	30-55%	First-line for all benefit groups
Ezetimibe	Cholesterol absorption inhibitor	15-20%	Add-on to statin; statin-intolerant
PCSK9 Inhibitors	Alirocumab, evolocumab (SC q2-4wk); inclisiran (SC q6mo)	50-60%	ASCVD/FH not at goal on max tolerated statin ± ezetimibe
Bempedoic Acid	ATP-citrate lyase inhibitor (oral)	15-25%	Statin-intolerant; add-on
Fibrates	Fenofibrate	Modest	High TG (≥500) for pancreatitis prevention
Icosapent Ethyl	Pure EPA 4g/day	Minimal	ASCVD + TG 135-499 on statin (REDUCE-IT)

Familial Hypercholesterolemia (FH)

Autosomal dominant (LDLR, APOB, PCSK9). LDL-C >190 adult, >160 child.
Cascade screening essential. Early high-intensity statin ± ezetimibe ± PCSK9 inhibitor.

Monitoring

Fasting lipid panel 4-12 weeks after initiation/change, then every 3-12 months.
Liver function tests at baseline, 12 weeks, then as needed (statins).
Assess adherence, side effects (myalgia – often nocebo; true myopathy rare).

Special Populations

Elderly (>75): Individualize; consider frailty, polypharmacy, goals of care. RCT evidence supports benefit in primary prevention.
Pregnancy: Statins contraindicated (historical category X; now individualized for very high risk). Bile acid sequestrants if needed.
Children: Screen at 9-11 years and 17-21 years. FH: start statin at 8-10 years.

Conclusion

Cholesterol management is a cornerstone of ASCVD prevention. Risk-based LDL-C targets, lifestyle foundation, and potent pharmacotherapy (statins ± ezetimibe ± PCSK9 inhibitors) achieve dramatic risk reduction. Emerging targets (Lp(a), inflammation) promise further refinement.