Hyperlipidemia

Definitions: 

Dyslipidemiaa broad term describing disorders of lipoprotein metabolism, including overproduction or deficiency.

Hyperlipidemia: a condition characterized by ↑ serum levels of total cholesterol, low-density lipoprotein cholesterol (LDL), or non-high-density lipoprotein cholesterol (HDL).

Atherosclerotic cardiovascular disease (ASCVD): acute coronary syndromes, history of myocardial infarction (MI), stable angina, coronary, or other arterial revascularization, stroke, transient ischemic attack (TIA), Peripheral artery disease (PAD) of atherosclerotic origin. 
 

Types:

Familial: ​
 

 Secondary:  

  • Endocrine disorders: hypothyroidism, DM, Cushing’s syndrome.

  • Renal disorders: nephrotic syndrome, uremia. 

  • Chronic liver disease.

  • Medications: glucocorticoids, estrogen, thiazide diuretics, blockers, isotretinoin.

  • Pregnancy.  

High HDL= Negative risk factor for CAD. 

Study guide:

Risk factors:

  • Age: Cholesterol levels increase with age until the age 65.

  • Physical inactivity.

  • Metabolic syndrome (Figure1).

  • Family history of hyperlipidemia.

  • DM type II.

  • Medications (mentioned above).

  • Gender:

    1. Men > women before menopause.

    2. Men ≤ women after menopause.

  • Diet:

    1. High calorie diet (simple sugars) -> increases triglyceride (TG).

    2. Saturated fatty acids -> increase LDL and cholesterol. 

Diagnosing criteria 

  • Large waist circumference — a waistline that measures at least 35 inches (89 centimeters) for women and 40 inches (102 centimeters) for men

  • High triglyceride level — 150 milligrams per deciliter,(mg/dL), or 1.7 millimoles per liter (mmol/L), or higher of this type of fat found in blood

  • Reduced high-density lipoprotein (HDL) cholesterol — less than 40 mg/dL (1.04 mmol/L) in men or less than 50 mg/dL (1.3 mmol/L) in women of this "good" cholesterol

  • Increased blood pressure — 130/85 millimeters of mercury (mm Hg) or higher

  • Elevated fasting blood sugar — 100 mg/dL (5.6 mmol/L) or higher

Pathophysiology: 

  • Sources of TG:

    • Intestines produce -> chylomicrons through lymphatic system.

    • Liver produces -> very low density lipoprotein VLDL.

  • In the blood stream, TG in chylomicrons and VLDL are degraded by lipoprotein lipase into free fatty acids -> stored in tissues (e.g. adipose tissue).

  • Chylomicron remnants are endocytosed by the liver. 

  • LDL, carrying cholesterol, is endocytosed by hepatic and extrahepatic tissues. 

 

Diagnosis: 

  • Diagnostic criteria:

    • 2 fasting lipid panels on 2 separate visits with abnormal results.  

    • For excluding secondary causes:

      • Thyroid stimulating hormone (TSH) (hypothyroidism)

      • Liver function test  (LFTs) (chronic liver disease)

      • Blood urea nitrogen (BUN), Cr, urinary proteins (nephrotic syndrome)

      • Glucose levels (DM)

  • Screening:

    • Adult:

      • Men ≥35 Y/O

      • Women≥45 Y/O

    • Children (if any of the following are present):

      • Family history of familial hyperlipidemia.

      • Family history of premature CAD.

      • Obesity.

 

Clinical Presentation:

  • Mostly asymptomatic.

    • In severe hyperlipidemia may present with:

      • Xanthelasma (yellow plaques on eyelid).

      • Xanthoma (irregular yellow nodule found on tendons).

      • Pancreatitis (hypertriglyceridemia). 

CVS Risk Assessment:

  • Smoking

  • HTN

  • Low HDL<35mg\dL

  • Age M>45, F>55

  • Male gender

  • Family history of

  • premature CAD 

CVS Risk Equivalent:

  • DM

  • Peripheral arterial disease

  • Abdominal aortic 
    aneurysm

  • Carotid artery 
    disease

  • Clinical coronary 
    artery disease

Management:

  • According to ATP IV guidelines, LDL goals are:

    • ≤ 1 CVS risk factor < 160 mg/dL

    • ≥ 2 CVS risk factors < 130 mg/dL

    • CVS risk equivalent:

      • If one diagnosis < 100 mg/dL

      • If two diagnoses < 70 mg/dL

  • Non-pharmacological treatment:

    • Diet control.

    • Smoking cessation.

    • Exercise. 

  • Pharmacological treatment:​​​

 Complications:

  • Atherosclerosis significantly increases risk of developing cardiovascular disease: 

  • Chest pain

  • Heart attacks

  • Strokes 

 

References:

  • Howland, Richard D et al. Pharmacology. Philadelphia: Lippincott Williams & Wilkins, 2006. Print.

  • Fischer, Conrad. Master The Boards. Print.

  • Agabegi, Steven S, Elizabeth D Agabegi, and Adam C Ring. Step-Up To Medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2013. Print.

  • Mayoclinic.org,. 'High Cholesterol - Mayo Clinic'. N.p., 2015. Web. 3 Nov. 2015.

  • At a glance, ATP III. 'ATPIII At A Glance A Quick Desk Reference'. NHLBI. N.p., 2015. Web. 3 Nov. 2015.

  • Uspharmacist.com,. 'Uspharmacist.Com > Metabolic Syndrome: Risk Factors And Recommendations'. N.p., 2015. Web. 3 Nov. 2015. (Figure1)

  • Organiconline.com.sg,. 'Organic Online Naturalis Xanthelasma Treatment'. N.p., 2015. Web. 3 Nov. 2015. (Figure2)

  • Wallpaper222,. '20 Awesome Mac Silver Dawn Eyeshadow Images'. N.p., 2015. Web. 3 Nov. 2015. (Figure3)

Written by:    Haifa Al Issa


Reviewed by: Sara Qubaiban
                       Roaa Amer


Format Editor: Adel Yasky 

                          Bayan Alzomaili

Audio recording:
- ​Read by: Bayan Alzomili
- Directed by: Rana Alzahrani
- Audio production: Bayan Alzomaili