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Lipid disorders

Last updated: September 17, 2021

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Lipid disorders encompass a broad spectrum of metabolic conditions that affect blood lipid levels. They are generally characterized by elevated levels of cholesterol, triglycerides, and/or lipoproteins in the blood (hyperlipoproteinemias), which are often associated with an increased risk of (or current) cardiovascular disease. Hyperlipoproteinemias are most commonly caused by lifestyle factors (diet, lack of activity, alcohol consumption). However, they may also be congenital, as is the case with familial hypertriglyceridemia, which is associated with extremely high levels of triglycerides that significantly increase the risk of pancreatitis, and familial hypercholesterolemia, which results in early atherosclerotic complications. Lipid disorders are usually detected during routine laboratory testing, such as cardiovascular risk factor screening. The blood lipid profile includes total cholesterol, LDL, HDL, and triglycerides. Treatment of hyperlipidemia is indicated to reduce the risk of cardiovascular disease in patients with LDL > 190 mg/dL, diabetes mellitus, and clinical ASCVD, and should be considered for other patients with a 10-year ASCVD risk score ≥ 7.5% after discussion of the risks and benefits. Lifestyle modifications and lipid-lowering agents (primarily statins) are the main treatment modalities. Abetalipoproteinemia is a congenital lipid disorder characterized by a deficiency of apolipoproteins (hypolipoproteinemia), which leads to impaired intestinal absorption of fats and fat-soluble vitamins. Symptoms, which usually appear early, mainly consist of failure to thrive, steatorrhea, and signs of vitamin E deficiency. The treatment includes supplementation of vitamin E.

  • Dyslipidemia: an abnormal concentration of lipids in the blood (e.g., high LDL, low HDL)
  • Hyperlipidemia: elevated blood lipid levels (total cholesterol, LDL, triglycerides)
  • Hypercholesterolemia: total cholesterol > 200 mg/dL
  • Hypertriglyceridemia: triglyceride levels > 150 mg/dL
  • Hyperlipoproteinemia: elevated levels of certain lipoproteins

Epidemiological data refers to the US, unless otherwise specified.

Frederickson classification of inherited hyperlipoproteinemias [3]
I IIa IIb III IV V
Condition
  • Familial hyperchylomicronemia [4]
  • Familial hypercholesterolemia [5]
  • Familial combined hyperlipidemia [6]
  • Familial hypertriglyceridemia [8]
  • Mixed hyperlipidemia [9]
Frequency [10]
  • Rare
  • 1:50–1:200
  • 1:1000–1:5000
  • 1:50–1:100
  • Very rare
Inheritance
Pathogenesis
  • Hepatic overproduction of VLDL or defective ApoA-V
  • Defective ApoA5
Clinical manifestations
Lipoprotein defect
Total cholesterol
  • Normal to mildly ↑
  • Massively ↑
  • Normal to mildly ↑
Elevated serum lipoproteins
Total triglycerides
  • Massively ↑
  • Can be > 2,000 mg/dL
  • Normal
  • Massively ↑
  • Massively ↑
Overnight plasma
  • Creamy top layer
  • Clear
  • Clear
  • Turbid
  • Turbid
  • Creamy top and turbid bottom layer

Dyslipidemia is a major risk factor for atherosclerotic cardiovascular disease.

There are typically no specific signs or symptoms.

Skin manifestations

Xanthomas

  • Description: nodular lipid deposits in the skin and tendons
  • Pathophysiology: Extremely high levels of triglycerides and/or LDL result in extravasation of plasma lipoproteins and their deposition in tissue.
  • Types
Types of xanthomas
Description Location Associated condition
Eruptive xanthoma
  • Yellow papules with an erythematous border
  • May be tender and itchy
  • Buttocks, back, and extensor surfaces of the extremities
Tuberous xanthoma
  • Firm, painless, reddish-yellow nodules located in pressure areas
  • Severe hypercholesterinemia (LDL and/or VLDL levels)

Tendinous xanthoma

  • Firm nodules, located in tendons
  • Severe hypercholesterinemia (LDL and/or VLDL levels)

Palmar xanthoma

  • Palms of the hands

Plane xanthoma

  • Larger body areas, e.g., trunk, neck, shoulders

:

Xanthelasmas

Eye manifestations

Gastrointestinal manifestations

Premature atherosclerosis

Approach [11]

Lipid profile [11]

Parameters of fat metabolism [17]
Laboratory parameter Optimal level Abnormal levels
Total cholesterol
  • < 200 mg/dL
  • Borderline: 200–239 mg/dL
  • High: ≥ 240 mg/dL
Triglycerides
  • < 150 mg/dL
  • Borderline: 150–199 mg/dL
  • High: 200–499 mg/dL
  • Very high: ≥ 500 mg/dL
LDL
  • < 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
HDL
  • ≥ 60 mg/dL
  • Low: < 40 mg/dL
LDL/HDL ratio [18]
Total cholesterol/HDL ratio [18]

Assessment for secondary causes of hyperlipidemia [11]

Approach [11]

  • Encourage all patients to make lifestyle modifications (see “Primary prevention of ASCVD”).
  • Initiate pharmacologic therapy based on the patient's age, LDL level, and ASCVD risk.
  • Patients with familial lipid disorders [15]
    • Consider specialist referral.
    • Treatment should involve lifestyle modifications and pharmacologic therapy with individualized treatment goals.
  • Xanthomas and xanthelasmas can be treated for cosmetic reasons, but recurrence is common. [22][23]

The goal of treatment is to reduce the risk of cardiovascular diseases. Therefore, the decision to treat hypercholesterolemia should be based on a patient's 10-year ASCVD risk.

In severe hypercholesterolemia (LDL ≥ 190 mg/dL) that is not adequately controlled with medical therapy, LDL apheresis may be used in consultation with a lipid specialist. [11]

Treatment of hypercholesterolemia in adults [11]

Indications for treatment [11]

If high-intensity statin therapy is indicated but not tolerated, consider moderate-intensity statins or low-intensity statins. [11]

Statins [11]

Statins used for lipid-lowering therapy in adults [11]

Statin intensity Expected reduction in LDL level Agents

High intensity

  • ≥ 50%
Moderate intensity
  • 30–49%
Low intensity
  • < 30%

Nonstatin lipid-lowering agents [11]

Treatment of hypertriglyceridemia in adults

In patients with intermediate to high ASCVD risk, the risk-benefit assessment should take hypertriglyceridemia into account. Moderate to severe hypertriglyceridemia is generally a factor that favors statin therapy. [11]

Treatment of hypertriglyceridemia in adults [11]
Definition Treatment
Moderate hypertriglyceridemia
  • Fasting or nonfasting TG 175–499 mg/dL
  • In all patients > 20 years
Severe hypertriglyceridemia

Treatment of dyslipidemia in children [12]

Base treatment decisions on average of ≥ 2 fasting lipid panels taken within 2 weeks to 3 months of each other. The goal of medical therapy is to lower LDL to ≤ 130 mg/dL.

See “Primary prevention of ASCVD” and “Secondary prevention of ASCVD.”

  1. Rosenson RS, JP Kastelein JJP. Hypertriglyceridemia. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/hypertriglyceridemia.Last updated: February 28, 2017. Accessed: January 14, 2018.
  2. HYPERLIPOPROTEINEMIA, TYPE I. https://www.omim.org/entry/238600. Updated: September 7, 2016. Accessed: April 3, 2019.
  3. HYPERLIPOPROTEINEMIA, TYPE II, AND DEAFNESS. https://www.omim.org/entry/144300. Updated: January 21, 2009. Accessed: April 3, 2019.
  4. Rosenson RS, Durrington P. Inherited disorders of LDL-cholesterol metabolism other than familial hypercholesterolemia. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/inherited-disorders-of-ldl-cholesterol-metabolism-other-than-familial-hypercholesterolemia.Last updated: March 27, 2018. Accessed: April 3, 2019.
  5. HYPERLIPOPROTEINEMIA, TYPE III. https://www.omim.org/entry/617347. Updated: March 22, 2018. Accessed: April 3, 2019.
  6. HYPERLIPOPROTEINEMIA, TYPE IV. https://www.omim.org/entry/144600. Updated: November 22, 2010. Accessed: April 3, 2019.
  7. HYPERLIPOPROTEINEMIA, TYPE V. https://www.omim.org/entry/144650. Updated: June 3, 2018. Accessed: April 3, 2019.
  8. Bays HE, Jones PH, Orringer CE, Brown WV, Jacobson TA. National Lipid Association Annual Summary of Clinical Lipidology 2016. Journal of Clinical Lipidology. 2016; 10 (1): p.S1-S43. doi: 10.1016/j.jacl.2015.08.002 . | Open in Read by QxMD
  9. Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2018; 139 (25). doi: 10.1161/cir.0000000000000625 . | Open in Read by QxMD
  10. National Heart, Lung, and Blood Institute. Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents: Summary Report. Pediatrics. 2011; 128 (Supplement): p.S213-S256. doi: 10.1542/peds.2009-2107c . | Open in Read by QxMD
  11. Bibbins-Domingo K, Grossman DC, et al. Screening for Lipid Disorders in Children and Adolescents. JAMA. 2016; 316 (6): p.625-33. doi: 10.1001/jama.2016.9852 . | Open in Read by QxMD
  12. Sturm AC, Knowles JW, Gidding SS, et al. Clinical Genetic Testing for Familial Hypercholesterolemia. J Am Coll Cardiol. 2018; 72 (6): p.662-680. doi: 10.1016/j.jacc.2018.05.044 . | Open in Read by QxMD
  13. McGowan MP, Hosseini Dehkordi SH, Moriarty PM, Duell PB. Diagnosis and Treatment of Heterozygous Familial Hypercholesterolemia. Journal of the American Heart Association. 2019; 8 (24). doi: 10.1161/jaha.119.013225 . | Open in Read by QxMD
  14. Sampson M, Ling C, Sun Q, et al. A New Equation for Calculation of Low-Density Lipoprotein Cholesterol in Patients With Normolipidemia and/or Hypertriglyceridemia. JAMA Cardiol. 2020; 5 (5): p.540-548. doi: 10.1001/jamacardio.2020.0013 . | Open in Read by QxMD
  15. Third report of the National Cholesterol Education Program (NCEP) Expert Panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III) final report. https://www.nhlbi.nih.gov/files/docs/resources/heart/atp-3-cholesterol-full-report.pdf. Updated: September 1, 2002. Accessed: May 10, 2017.
  16. Millán J, Pintó X, Muñoz A, et al. Lipoprotein ratios: Physiological significance and clinical usefulness in cardiovascular prevention.. Vasc Health Risk Manag. 2009; 5 : p.757-65.
  17. Stone NJ, Robinson JG, Lichtenstein AH et al. 2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults. Journal of the American College of Cardiology. 2014; 63 (25). doi: 10.1016/j.jacc.2013.11.002 . | Open in Read by QxMD
  18. Goldberg IJ. Diabetic Dyslipidemia: Causes and Consequences. J Clin Endocrinol Metab. 2001; 86 (3): p.965-971. doi: 10.1210/jcem.86.3.7304 . | Open in Read by QxMD
  19. Vodnala D, Rubenfire M, Brook RD. Secondary Causes of Dyslipidemia. Am J Cardiol. 2012; 110 (6): p.823-825. doi: 10.1016/j.amjcard.2012.04.062 . | Open in Read by QxMD
  20. Rohrich RJ, Janis JE, Pownell PH. Xanthelasma Palpebrarum: A Review and Current Management Principles. Plast Reconstr Surg. 2002; 110 (5): p.1310-4. doi: 10.1097/01.prs.0000025626.70065.2b . | Open in Read by QxMD
  21. Sathiyakumar V; Jones SR; Martin SS. Fitzpatrick's Dermatology, Ninth Edition, 2-Volume Set. McGraw-Hill Education / Medical ; 2019
  22. Karr S. Epidemiology and management of hyperlipidemia.. Am J Manag Care. 2017; 23 (9 Suppl): p.S139-S148.
  23. Earl S. Ford, Wayne H. Giles, William H. Dietz. Prevalence of the Metabolic Syndrome Among US Adults. JAMA. 2002; 287 (3): p.356. doi: 10.1001/jama.287.3.356 . | Open in Read by QxMD