# Dyslipidemia
**Dyslipidemia** is an abnormal concentration of one or more lipids or lipoproteins in the blood, including elevated cholesterol, elevated triglycerides, elevated lipoprotein(a), or a low high-density lipoprotein cholesterol (HDL-C) level that contributes to the development of atherosclerosis[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full) • [2](https://www.acc.org/About-ACC/Press-Releases/2026/03/13/18/01/ACCAHA-Issue-Updated-Guideline-for-Managing-Lipids-Cholesterol). Its clinical importance lies in the prevention of atherosclerotic cardiovascular disease (ASCVD), which includes acute coronary syndromes, stroke, transient ischemic attack, and peripheral artery disease[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full).
| Key fact | Detail |
|---|---|
| Definition | Elevation of plasma cholesterol, triglycerides, or both, or a low HDL-C level contributing to atherosclerosis; no precise numeric threshold separates normal from abnormal[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full) |
| Main goal of treatment | Prevention of ASCVD, including acute coronary syndromes, stroke, TIA, and peripheral artery disease[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full) |
| Burden | 86.4 million US adults age 20 or older had high or borderline high total cholesterol (≥200 mg/dL) from 2017 to 2020[3](https://www.cdc.gov/cholesterol/testing/index.html) |
| Screening | First lipid profile by age 19; one test for children at ages 9 to 11; adults with normal levels retested about every 5 years[4](https://www.medlineplus.gov/ency/article/000403.htm) |
| First-line drug therapy | Statins, as an adjunct to healthy lifestyle intervention[5](https://www.jacc.org/doi/10.1016/j.jacc.2018.11.003) |
| Very high risk secondary prevention goal | LDL-C <55 mg/dL (1.4 mmol/L) and non-HDL-C <85 mg/dL (2.2 mmol/L)[6](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know) |
| Current US guideline | The 2026 ACC/AHA multisociety Guideline on the Management of Dyslipidemia, which replaces the 2018 blood cholesterol guideline[7](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia?trk=article-ssr-frontend-pulse_little-text-block) |
## Classification and causes
Dyslipidemias are commonly grouped by the pattern of elevation: isolated hypercholesterolemia (cholesterol only), isolated hypertriglyceridemia (triglycerides only), or mixed hyperlipidemia (both)[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full). A practical distinction separates primary (genetic) causes from secondary causes, and both often contribute in the same patient; in familial combined hyperlipidemia, for example, expression may occur only in the presence of significant secondary causes[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full).
Primary dyslipidemias result from gene mutations that cause overproduction or defective clearance of LDL or triglycerides, or underproduction or excessive clearance of HDL[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full). [Familial hypercholesterolemia](https://www.edgepedia.org/familial-hypercholesterolemia), caused by an LDL receptor defect, affects about 1 in 200 heterozygotes and produces tendon xanthomas, arcus corneae, and premature coronary artery disease; homozygotes, roughly 1 in 250,000 to 1 in 1 million, develop coronary disease before age 18[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full). Familial combined hyperlipidemia is more common, at 1 in 50 to 1 in 100, and is responsible for approximately 15% of myocardial infarctions in people under 60[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full).
**Secondary causes** contribute to many cases in adults. In wealthy nations, the leading secondary cause is physical inactivity combined with a diet containing too many total calories, saturated fat, cholesterol, and trans fats.[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full) Other common causes include diabetes mellitus, chronic kidney disease, cholestatic liver disease such as primary biliary cirrhosis, hypothyroidism, alcohol overuse, and medications including thiazides, beta-blockers, retinoids, antiretroviral agents, cyclosporine, tacrolimus, progestins, and glucocorticoids[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full). Diabetes produces a particularly atherogenic pattern of high triglycerides, small dense LDL particles, and low HDL[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full).
## Diagnosis and screening
Diagnosis is by a blood test, the lipid profile, which measures total cholesterol, triglycerides, and HDL-C directly and is used to calculate LDL-C and VLDL-C[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full). Because high cholesterol usually causes no symptoms, screening is the usual route to diagnosis[3](https://www.cdc.gov/cholesterol/testing/index.html). ACC/AHA guidelines call for a first lipid profile by age 19, with one test for children at ages 9 to 11 to check for familial hypercholesterolemia or other lipid problems, and follow-up testing every 5 years for adults with normal levels, sooner after lifestyle changes, and more often for adults with elevated cholesterol, diabetes, kidney problems, or vascular disease[4](https://www.medlineplus.gov/ency/article/000403.htm).
Because serum lipid levels are continuous, there is no precise boundary between normal and abnormal; the term dyslipidemia is applied to lipid levels for which treatment has proven beneficial[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full). In most patients with newly diagnosed dyslipidemia, clinicians test for secondary causes, including creatinine, fasting glucose or HbA1c, liver enzymes, thyroid-stimulating hormone, and urinary protein, and repeat these tests when the lipid profile worsens inexplicably[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full).
## Treatment
**Lifestyle first.** A healthy diet carries a Class 1A recommendation for reducing cardiovascular events, and the 2026 guideline emphasizes earlier intervention through maintaining a healthy weight, regular physical activity, avoiding tobacco, and healthy sleep[8](https://doi.org/10.1161/cir.0000000000001423) • [2](https://www.acc.org/About-ACC/Press-Releases/2026/03/13/18/01/ACCAHA-Issue-Updated-Guideline-for-Managing-Lipids-Cholesterol).
**Statins as the foundation.** Among lipid-lowering drugs, statins are the cornerstone of therapy alongside healthy lifestyle interventions[5](https://www.jacc.org/doi/10.1016/j.jacc.2018.11.003). A Cochrane review of 18 randomized trials with 56,934 participants without prior cardiovascular disease found that statins reduced all-cause mortality (OR 0.86, 95% CI 0.79 to 0.94), combined fatal and nonfatal cardiovascular events (RR 0.75), and revascularization (RR 0.62); of 1,000 people treated for five years, 18 would avoid a major cardiovascular event[9](https://www.cochrane.org/evidence/CD004816_statins-primary-prevention-cardiovascular-disease). The US Preventive Services Task Force recommends prescribing a statin for primary prevention in adults aged 40 to 75 who have one or more cardiovascular risk factors (dyslipidemia, diabetes, hypertension, or smoking) and an estimated 10-year risk of 10% or greater, and finds the evidence insufficient for adults 76 or older[10](https://www.uspreventiveservicestaskforce.org/uspstf/index.php/recommendation/statin-use-in-adults-preventive-medication).
**Nonstatin therapy.** For patients on maximally tolerated statin therapy who need further LDL-C lowering to reach goal, adding ezetimibe, a PCSK9 monoclonal antibody, or bempedoic acid reduces ASCVD risk[8](https://doi.org/10.1161/cir.0000000000001423). For severe hypertriglyceridemia, treatment to prevent pancreatitis may include triglyceride-lowering therapies, especially at triglyceride levels of 1000 mg/dL (11.3 mmol/L) or higher; in a phase 3 trial of genetically confirmed familial chylomicronemia syndrome, the apoC3 antisense oligonucleotide olezarsen at 80 mg reduced triglycerides by 43.5% at 6 months compared with placebo[6](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know) • [8](https://doi.org/10.1161/cir.0000000000001423).
## The 2026 guideline and what changed
The 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline retires and replaces the 2018 blood cholesterol guideline and is retitled to reflect the growing understanding of ASCVD risk from atherogenic lipoproteins beyond LDL-C, including triglyceride-rich remnant particles and lipoprotein(a)[7](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia?trk=article-ssr-frontend-pulse_little-text-block). Its main updates are:
- **PREVENT equations replace the Pooled Cohort Equations** for 10- and 30-year ASCVD risk assessment in primary prevention for adults aged 30 to 79, with a "CPR" model of calculating risk, personalizing it with factors the equations omit, and possibly reclassifying with coronary artery calcium scoring[6](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know).
- **Lowered treatment thresholds.** LDL-lowering therapy can be considered at a 10-year PREVENT-ASCVD risk of 3% to under 5% (borderline) and should be considered at 5% to under 10% (intermediate) after a clinician-patient discussion[6](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know).
- **Return of treatment goals.** LDL-C and non-HDL-C goals again guide therapy, with lower targets for higher-risk groups; very high risk secondary prevention patients have goals of LDL-C under 55 mg/dL and non-HDL-C under 85 mg/dL[6](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know).
- **Broader testing.** Lp(a) is to be measured at least once in a lifetime, with selective apolipoprotein B measurement, and expanded use of coronary artery calcium scoring to reclassify risk[7](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia?trk=article-ssr-frontend-pulse_little-text-block).
- **Earlier treatment across the lifespan.** Health behavior counseling should start in youth, with early pharmacotherapy considered in youth with familial hypercholesterolemia and in young adults with LDL-C of 160 mg/dL or higher or a strong family history of premature ASCVD[6](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know).
The population effect of these changes depends on which recommendation class is applied. One modeling study estimated that at the class 1 threshold, the number of US adults receiving or recommended for statin therapy decreased by about 3.0 million (95% CI, 2.3 to 3.6 million), with larger reductions among Black adults, men, and adults aged 50 to 69, while at the class 2 threshold the new 30-year risk assessment substantially expanded recommendations, particularly among younger adults[11](https://arxiv.org/abs/2605.10979).
## Measurement targets and debate
General lipid targets used in practice include LDL-C below 100 mg/dL for people at moderate risk, below 70 mg/dL at high risk or with diabetes, and below 55 mg/dL after a heart attack or stroke; HDL-C of 60 mg/dL or higher; total cholesterol below 200 mg/dL; and triglycerides below 150 mg/dL[4](https://www.medlineplus.gov/ency/article/000403.htm). Which measure should anchor therapy remains a live question: the National Lipid Association's expert panel held that non-HDL-C is a better primary target for modification than LDL-C, because it captures atherogenic remnant particles as well[12](https://www.lipidjournal.com/article/S1933-2874%2815%2900059-8/fulltext). HDL-C, though predictive in the general population, is not a straightforward treatment target, since genetically high or low HDL-C does not always correspond to proportionally lower or higher cardiovascular risk[1](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full).
## References
1. [Dyslipidemia, Merck Manual Professional Edition](https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/dyslipidemia?media=full)
2. [ACC/AHA Issue Updated Guideline for Managing Lipids, Cholesterol, American College of Cardiology](https://www.acc.org/About-ACC/Press-Releases/2026/03/13/18/01/ACCAHA-Issue-Updated-Guideline-for-Managing-Lipids-Cholesterol)
3. [Testing for Cholesterol, CDC](https://www.cdc.gov/cholesterol/testing/index.html)
4. [High blood cholesterol levels, MedlinePlus Medical Encyclopedia](https://www.medlineplus.gov/ency/article/000403.htm)
5. [2018 AHA/ACC Multisociety Guideline on the Management of Blood Cholesterol, JACC](https://www.jacc.org/doi/10.1016/j.jacc.2018.11.003)
6. [Top Things to Know: 2026 Guideline on the Management of Dyslipidemia, American Heart Association](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia/top-things-to-know)
7. [2026 Guideline on the Management of Dyslipidemia, American Heart Association](https://professional.heart.org/en/science-news/2026-guideline-on-the-management-of-dyslipidemia?trk=article-ssr-frontend-pulse_little-text-block)
8. [2026 ACC/AHA Multisociety Guideline on the Management of Dyslipidemia, Circulation](https://doi.org/10.1161/cir.0000000000001423)
9. [Statins for the primary prevention of cardiovascular disease, Cochrane](https://www.cochrane.org/evidence/CD004816_statins-primary-prevention-cardiovascular-disease)
10. [Statin Use for the Primary Prevention of Cardiovascular Disease in Adults, USPSTF](https://www.uspreventiveservicestaskforce.org/uspstf/index.php/recommendation/statin-use-in-adults-preventive-medication)
11. [Statin Recommendations among US Adults with the 2026 Dyslipidemia Guidelines, arXiv](https://arxiv.org/abs/2605.10979)
12. [National Lipid Association Recommendations for Patient-Centered Management of Dyslipidemia: Part 1, Journal of Clinical Lipidology](https://www.lipidjournal.com/article/S1933-2874%2815%2900059-8/fulltext)
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*Topic: Encyclopedia › Life and health › Human health and medicine › Diseases and injuries › Digestive, metabolic, and endocrine conditions › Inherited and other metabolic disorders*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Sep 30, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
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