Card Set Information
Lecture 40 Disorders of lipoprotein metabolism
What is dyslipidemia?
Any abnormal concentration of lipid (C, CE, or TAG) in the blood
What is hyperlipidemia?
elevated levels of lipids in the blood
What is hypolipidemia?
reduced levels of lipids in the blood
What is primary dyslipidemia?
dyslipidemia caused by an
in lipoprotein metabolism
What is secondary dyslipidemia?
dyslipidemia caused by another disease (ex. obesity, diabetes mellitus, hypothyroidism)
What is the most common serum profile of dyslipidemia?
hypertriacylglycerolemia and reduced levels of HDL cholesterol
Why is a blood sample taken after a 12 hour fast?
to make sure there are no CM from the previous meal
What is the Friedwald Equation?
LDL-C = Total-C - VLDL-TAG/5 - HDL-C
What is type IIa hyperlipidemia?
Elevated LDL, familial hypercholesteremia
Deficiency of LDL receptor expression
Increase of LDL, elevated C, normal TAG
Heterozygous common, homozygous rare
Xanthomata (accumulation of lipids) on extremities, corneal arcus, atherosclerosis; risk of cardiovascular disease
Diet; reduce intake of cholesterol and fat, combination therapy (HMG-CoA reductase inhibitor = statin and absorption inhibitor, also in combination with niacin
What is type I hyperlipidemia?
Familial chylomicronemia (elevated CM)
Deficiency in lipoprotein lipase and/or Apo C-II synthesis or function
Elevated fasting CM, TAG elevated (fasting plasma turbid with milky CM forming creamy top layer, C normal
Eruptive xanthomata, hepatosplenomegaly, pancreatitis
No drug therapy, only dietary fat restriction, fat soluble vitamin supplements, diet with medium and short chain TAG (tropical oils) avoid CM production
What is type IV hyperlipidemia?
Cause? Primary? Secondary?
Elevated VLDL, familial hypertriglyceridemia
Primary-VLDL overproduction and/or decreased VLDL removal, Secondary-obesity, ethanol intake, estrogen use, insulin resistance
Common (1 in 300)
Serum opaque, few clinical manifestations, if C elevated=elevated risk of cardio-vascular disease
Correct secondary causes by diet/life style changes, combination therapy
What is type IIb hyperlipidemia?
Causes? Primary? Secondary?
Elevated LDL and VLDL, familial combined hyperlipidemia
Primary-overproduction of Apo B-100, Secondary-cluster of precipitating factors; obesity, glucose intolerance, insulin resistance, hypertension
Elevated VLDL, TAG elevated, LDL elevated, C elevated, HDL usually decreased
Common (1 in 200)
No xanthomata, high risk of premature CVD
Aggressive treatment, diet, life style, weight loss, combination therapy
What is type III hyperlipidemia?
Elevated IDL, familial dysbetalipoproteinemia
Polymorphism of Apo E gene(ligand for hepatic Apo E receptor)
VLDL remnants (=IDL) and CM remnants elevated, TAG and C elevated
Tuberoeruptive and/or striate palmar xanthomata, premature coronary and peripheral vascular diseases
Diet, combination therapy
What are scavenger receptors (type A)?
Receptors on macrophages for damaged LDL (insensitive to cholesterol levels=continuos uptake of damaged LDL
What do macrophages (foam cells) release that leads to an atherosclerosic plaque?
Cytokines (stimulate inflammation, immune response, collagen synthesis, proliferation of smooth muscle cells, accumulation of calcium)
What are the two best treatments for reducing LDL-C?
Statins (HMG CoA reductase inhibitors) and Resins
What are two of the best ways to increase HDL-C levels?
Fibrates (increase expression of Apo A-I)
Niacin (decrease catabolism of Apo A-I)
What is abetalipoproteinemia (CM retention disease)?
Loss of function, mutation in gene encoding MTP (microsomal transfer protein)
: transfers lipids to nascent CM and VLDL before they are released from enterocytes and hepatocytes
What is Tangier disease (alphalipoprotein deficiency)?
Defect in ATP binding cassette protein A1 (ABC-A1)
What does ATP binding cassette protein A1 (ABC-A1) do?
Transfers C from peripheral cells to HDL