Lipid Metabolism

What are lipoproteins?

Fat particles that are bound to and encased in protein entities floating in the bloodstream

What is the primary role of lipoproteins in the body?

transport lipids between the liver, intestines & tissues

What are the support functions of lipoproteins in the body?

- energy storage and use

- hormone production

- contributes to cell membrane structure

What are different types of lipoproteins?

- VLDL (very low-density lipoprotein)

- LDL (low-density lipoprotein)

- HDL (high-density lipoprotein)

- Chylomicron

what is the function of chylomicrons?

- deliver triglycerides (TGs) to peripheral tissues

- deliver cholesterol to the liver as chylomicron remnants

What is the function of VLDL?

delivers hepatic TGs to peripheral tissues

What is the function of IDL (intermediate density lipoprotein)?

delivers TGs and cholesterol to the liver

What are the breakdown products of IDLs?

LDLs

What is the function of LDL?

delivers hepatic cholesterol to peripheral tissues

What is the function of HDL?

mediates reverse cholesterol from tissue

Which class of lipoprotein plays an opposite role compared to LDL in that it aids in the removal of tissue cholesterol?

HDL

What is the most common cause of dyslipidemia?

- ↑ LDL (#1)

- ↑ TGs

- ↓ HDL

What are the two most common types of dyslipidemias?

- familial combined hyperlipidemia

- familial hypertriglyceridemia

What is hypertriglyceridemia?

elevated blood triglycerides

complications associated with hypertriglyceridemia?

increase risk of:

- pancreatitis

- metabolic syndrome

- cardiovascular disease

most common cause of hypertriglyceridemia?

excess adiposity

what is the defect in familial hypercholesterolemia?

- Genetic defect in the LDL receptor

- Reduced or absent LDL mainly in hepatocytes but all nucleated cells have LDL-Rs

- Could also be defective apo B-100 which is the ligand for the LDL receptor

Statins MOA

inhibit HMG-CoA reductase

Other drug treatments for high cholesterol?

- PCSK9 inhibtors

- Niacin (vitamin b3)

PCSK9 inhibtors MOA

increases LDL receptor availability to bind LDL and clear it from circulation

Niacin MOA/concerns

- lowers TGs and LDL

- increases HDL

concerns: hepatotoxicity & T2DM

What is the first line drug treatment for high cholesterol?

statins

HDL normal levels

>40 mg/dL

LDL normal levels

nl < 100 mg/dL

Triglycerides normal levels

nl < 150 mg/dL

total cholesterol normal levels

nl < 200 mg/dL