Unit 6 Lipids

• Class A - HDL, Chylomicrons.
• Class B - VLDL, IDL, LDL
• Class C - Chylomicrons
• Class D – unknown function
• Class E – probably receptor on HDL
• and LDL.
• There is also ApoLp(a).

Normal carbohydrate and lipid diet for 2 preceding weeks.  Fast for 12 hours before specimen collection. (...only endogenous lipids)

Collect in Heparin Plasma for triglyceride assays.  Serum is acceptable but is known to trap a little TG.

Collect in Na₂EDTA plasma for Lipoprotein Electrophoresis.  

Keep refrigerated and do not freeze.

• Adults
• Optimal: <200 mg/dL
• Borderline: 200 – 239 mg/dL
• High Risk: >240 mg/dL
•                                             
• Children
• Optimal: <170 mg/dL
• Borderline: 170 – 199 mg/dL
• High Risk: >200 mg/dL

• Optimal: <150 mg/dL
• Borderline: 150 – 199 mg/dL
• High Risk: 200 – 499 mg/dL
• Very High: ≥500 mg/dL

• Optimal: >60 mg/dL
• High Risk: <40 mg/dL

Average Risk 3.5

Average Risk 5.0

• Mature >2.0 with PG+
• Borderline 1.6 - 2.0 with PG+
• Immature <1.6 with PG-

• Liebermann-Buchard
• *Reaction of cholesterol as an alcohol with a strong acid under high heat.
• *Reagents: Acetic Anhydride, Glacial Acetic Acid, strong Sulfuric Acid, and Sodium Sulfate.
• *Forms: Green Chromagen.

• Trinder Cholesterol Oxidase Method (similar to Glucose Oxidase)
• 1. De-esterify cholesterol with Cholesterol Ester Hydrolase.
• 2. Cholesterol Oxidase is used to form peroxide which is then used to form red chromophore.
• Interferents at the oxidation step (bilirubin, ascorbic acid, hemoglobin).

• Precipitation Method: Same as Cholesterol Oxidase method, only LDL and VLDL must be precipitated out using:
• 1. Heparin and MgCl₂
• 2. Dextrin Sulfate and Ca or Mg salt OR
• 3. MgCl₂ and Phosphotungstic Acid

• Direct Method:
• IgG antibodies against LDL, VLDL, and Chylomicrons.  
• Cholesterol Oxidase will not react with lipoprotein-antibody complexes.

LDL-C = Total Cholesterol - (HDL-C + TG/5)

• Assumptions: 
• Total Cholesterol = VLDL-C + LDL-C + HDL-C
• VLDL-C = TG/5

Glycerol Kinase Method

• 
• 
• End up with peroxide ⇒ Oxidized (colored) Dye

• Albumin- fastest - no name, FFA
• Alpha-1 - alpha, HDL, phospholipids
• Alpha-2 - pre-beta, VLDL, triglycerides
• Alpha 2/Beta Bridge - floating beta, IDL, cholesterol and triglycerides
• Beta - beta, LDL, cholesterol
• Gamma - slowest - no name, Chylomicrons

• AKA Deficiency in Lipoprotein Lipase Activity
• Serum: Clear with creamy layer of CM on top.
• Lipoprotein fraction: CM at point of application.
• Triglycerides: Elevated but from the CM.
• Cholesterol: normal to slightly increased.
• Chylomicrons: Present.  Individual cannot clear this from their blood.

• AKA Familial Hypercholesterolemia - common defect in LDL receptor gene leading to decreased ability to bind LDL and to internalize the LDL into cells.
• Serum: Clear and unremarkable.
• Lipoprotein fraction: Elevated Beta LP.
• Triglycerides: Normal.
• Cholesterol: Increased LDL with CHOL elevated.
• Chylomicrons: None in fasting individual.

• AKA Familial Combined Hyperlipidemia - common condition resulting in overproduction of small, dense atherogenic LDL and VLDL with unknown cause.
• Serum: Clear to faintly turbid due to TG.
• Lipoprotein fraction: Elevated Beta LP with slight elevation in Pre-Beta LP.
• Triglycerides and Cholesterol: Elevated.
• Chylomicrons: None in fasting individual.

• AKA Dysbetalipoproteinemia - Genetic and rare. Abnormal lipoprotein (IDL).
• Serum: Slightly turbid.  Possibly creamy CM on top.
• Lipoprotein fraction: Famous floating Beta band due to production of abnormal lipoprotein IDL (AKA β-VLDL).
• Triglycerides and Cholesterol: Elevated to about the same degree above the normal range.  Not uncommon for lipids to be 1,000 - 15,000 mg/dL.
• Chylomicrons: May or may not be present, but patients have a hard time clearing these remnants.
• It is essential to use Lipoprotein Electrophoresis to detect this HPL.

• AKA Hypertriglyceridemia - Most common of them all. Over production of large VLDL with abnormally high TG content while # of particles remains normal.
• Serum: Turbid.
• Lipoprotein fraction: Significant increase in Pre-Beta LP.
• Triglycerides: Elevated.
• Cholesterol: Normal to slightly elevated.
• Chylomicrons: None.

• Combination of Types I and IV - Deficiency of Lipoprotein Lipase and an increased production of VLDL
• Serum: Turbid with creamy CM layer on top.
• Lipoprotein fraction: Heavy band of CM at point of application and increase in Pre-Beta LP. (A non-fasting patient could also present this pattern.)
• Triglycerides: Elevated at a 5:1 ratio above cholesterol.
• Cholesterol: Elevated.
• Chylomicrons: Present.

• Adults
• Optimal <100 mg/dL
• Above Optimal 100 - 129 mg/dL
• Borderline 130 - 159 mg/dL
• High Risk 160 - 189 mg/dL
• Very High >190 mg/dL

• Children
• Optimal <90 mg/dL
• Above Optimal 90 - 109 mg/dL
• Borderline 110-129 mg/dL
• High Risk 130 - 149 mg/dL
• Very High >150 mg/dL