Lipids pt3
No description yet. This curated deck is ready for daily study.
Card preview (24)
Electrophoresis ● Electrophoretic pattern:
HDL (fastest), VLDL, LDL, Chylomicrons (barely moves)
Electrophoresis Preferred Supporting medium:
agarose gel - speed; sensitive; resolves lipoprotein classes
Electrophoresis Lipid-staining dyes: These stains react primarily with the ester bonds in triglycerides and cholesteryl esters
Oil Red O, Fat Red 7B, or Sudan Black B
● VLDL migrates with the alpha-2 globulin (pre beta) ● Chylomicrons, if present, remain at the origin
Electrophoresis
Methods ● It uses dextran sulfate (synthetic heparin) with magnesium (precipitants)
HDL
Methods CDC reference 3-step method-ultracentrifugation, heparin manganese precipitation and Abell-Kendall assay is utilized
HDL
the most popular method for measuring HDL-C these fully automated two reagent procedures do not require offline pretreatment (precipitation) and separation (hence the term “homogeneous”) and can be adapted to most chemistry analyzers.
Homogeneous assays
Method for LDL ●_ is the sample preferred for beta quantification.
EDTA plasma
Method for LDL combines ultracentrifugation and chemical precipitation
Beta quantification
Beta quantification ● Assumes cholesterol is mainly in VLDL, LDL, and HDL ● Plasma is ultracentrifuged for _ ● VLDL and chylomicrons float; LDL and HDL remain in solution ● Cholesterol in solution is measured ● LDL is precipitated for further analysis
≥18 hours
It is the most popular method for measuring HDL
Homogeneous Direct LDL-C Method
Common method for measuring LDL and HDL
Homogeneous Direct LDL-C Method
Not affected by high triglycerides (up to _ o Step 1: First reagent blocks non-LDL (or non-HDL) lipoproteins o Step 2: Second reagent releases LDL or HDL, which is then measured enzymatically
600 mg/dL) Homogeneous Direct LDL-C Method
It utilizes either Gel Chromatography or Affinity Chromatography
Chromatographic methods
It uses antibodies specific to epitopes on the apolipoproteins.
Immunochemical methods
It is based on the measurement of the turbidity created by apolipoprotein-antibody complexes
Immunoassay or Immunonephelometry - Apolipoprotein assay
Studies have shown that apo A-1 and apo B may be better indicators of atherosclerotic disease than lipoprotein assay
Immunoassay or Immunonephelometry - Apolipoprotein assay
currently considered the most important value in assessing cardiac risk and directing therapy.
LDL
LDL can be measured directly but is usually calculated using the _ ● Calculated values require evaluation of fasting samples.
Friedewald formula.
This method is unsuitable for non-fasting samples that contain chylomicrons or samples that contain B-VLDL
Friedewald Method (Indirect Method)
● It is an autosomal dominant disorder caused by defective or deficient LDL receptors. ● Clinical findings: (+) xanthelasma and planar (tendon) xanthomas
Familial Hypercholesterolemia (Type 2a)
It involves accumulation of plasma VLDL rich in cholesterol and chylomicron remnants
Familial Dysbetalipoproteinemia (Type 3 Hyperlipoproteinemia)
Familial Dysbetalipoproteinemia (Type 3 Hyperlipoproteinemia) Lab results:
Equal elevations of cholesterol and TAG and presence of B-VLDL
Clinical findings: xanthomas and premature vascular disease (coronary heart disease and peripheral artery disease)
Familial Dysbetalipoproteinemia (Type 3 Hyperlipoproteinemia)