Hyperlipidemia Flashcards
Definition of hyperlipidemia
LDL, total cholesterol, triglyceride, or lipoprotein level greater than 90th percentile
OR
HDL level less than 10th percentile
Benefit of HDL
regulates cholesterol levels to prevent atherosclerotic vascular disease
Primary hyperlipidemia
Familial - due to genetic disorder
Secondary hyperlipidemia
Acquired- originates from underlying factor such as diet, medication, hypothyroidism, diabetes
What is cholesterol?
circulating fatty substance that causes artherosclerosis
How much cholesterol should be obtained exogenously and endogenously?
exogenous: 300-700 mg per day
endogenous (made by liver): 800-1200 mg per day
What is hypercolesterolemia?
elevated LDL
When does atherososclerosis become symptomatic?
Until the plaque reaches 70-80% of the vessels diameter
How does atherosclerosis develop?
Endothelial damage occurs from the loss of nitric oxide in the endothelium, which increases inflammation at the site and allows lipids to accumulate.
Lipids are engulfed by macrophages and encapsulated by smooth muscle, creating a fibrotic plaque
What are foam cells?
Foam cells result from the engulfment of lipids by macrophages. Cholesterol builds up in foam cells and causes cell death and necrotic tissue.
Foam cells are encapsulated and protected by muscle, making a plaque
What are the 2 ways that plaques evolve?
- slowm chronic plaque buildup that eventually leads to stenosis
- Acute onset of rapid obstruction secondary to plaque rupture and thrombosis
What kinds of patient information is usesful in assessing hyperlipidemia risk?
- family hx of cardiovascular disease and hyperlipidemia
- diet and exercise
- tobacco and alcohol
- CAD, PAD, or angina history
- other med hx indicating increased risk
What is a lipid profile?
LDL, HDL, tryglycerides, and total cholesterol
Treatment course for hyperlipidemia
Exercise 30 min daily 5-6X per week
Low-saturated fat, low carb diet
Statins: pravastatin (40 mg), lovastatin (20-40 mg), atorvastatin (10 mg), rosuvastatin (10 mg)
How does HDL prevent atherosclerosis?
- transports cholesterol from walls of arteries to the liver
- antioxidant and anti-inflammatory - induces release of nitric oxide
Lipoproteins
Lipids are encapuslated by proteins because they are insoluble in plasma
- chylomicrons
- very-low-density lipoproteins
- intermediate-density lipoproteins
- low-density lipoproteins
- high-density lipoproteins
Which type of lipoprotein carries the most cholesterol?
LDL
Which lipoprotein carries the most triglycerides?
VLDLs (mostly tri with a little cholesterol and proteins)
What are the 2 pathways of production and transport of lipoproteins?
- Exogenous intestinal pathway
- Endogenous hepatic pathway
Exogenous pathway of lipoprotein transport
- Chylomicrons are made in wall of small intestine
- Chylomicrons transport triglycerides transport dietary triglycerides to peripheral tissues (especially fat and skeletal muscle)
- Remnant chylomicron particles contain dietary cholesterol and are taken up by liver
- Cholesterol is used to make VLDL or is excreted in bile
Endogenous pathway of lipoprotein transport
- the liver forms triglycerides, which is used to form VLDL
- VLDL carries trigylcerides to fat and muscle cells, where they are removed for energy and storage
- Resulting IDL (less tri and more cholesterol) go to liver
- IDL recycled to form VLDL with additional triglycerides or converted to LDL, which transfer cholesterol to HDL at peripheral tissues to be taken to liver for removal in the bile
Where does LDL go after it is made?
60% goes to liver
40% goes to extrahapatic tissues such as adrenal cortex and gonads (use cholesterol in cell membranes and steroid hormones)
How is HDL made?
- direct secretion by intestine and liver
3 stages of atherosclerosis
- fatty streaks
- fibrous atheromatous plaques
- complicated lesions
What is complicated atherosclerotic lesions?
Plaque breaks open and produces hemorrhage, ulceration and scar tissue due to slowing and turbulence of blood flow
