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Other tests that may be done to have a definitive diagnosis include:
Other tests that may be done to have a definitive diagnosis include:
*Studies of cells called fibroblasts (to see how the body absorbs LDL cholesterol)
*Studies of cells called fibroblasts (to see how the body absorbs LDL cholesterol)
*Gene analysis (to identify the defect associated with hyperlipidemia)
*Gene analysis or receptor analysis (to identify the specific defect associated with hyperlipidemia)
*Receptor analysis
Many different types of mutations have been identified in the LDL-receptor (LDLR) gene. They have been categorized into four classes of alleles based on the phenotypic behavior of the mutant protein:
*Class I - Null, in which LDL-receptor synthesis is defective.
*Class II - Transport defect, in which intracellular transport from the endoplasmic reticulum to the Golgi apparatus is defective.
*Class III - Binding defect, in which LDL-receptors are synthesized and transported to the cell surface normally, but binding of LDL-cholesterol is defective.
*Class IV - Internalization defect, in which the LDL-receptors reach the cell surface and bind LDL-cholesterol normally, but LDL internalization is defective.


===Approach===
===Approach===

Revision as of 19:26, 24 October 2012

Lipoprotein Disorders Microchapters

Patient Information

Overview

Causes

Classification

Hyperlipoproteinemia
Hypolipoproteinemia

Treatment

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hardik Patel, M.D., Aditya Govindavarjhulla, M.B.B.S. [2]

Overview

Laboratory Findings

Complete Lipid Profile

The US National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) suggests screening asymptomatic individuals with a complete fasting lipid profile every 5 years, with a shorter interval for those with high-normal lipid levels and longer interval for low-risk individuals with low or normal lipid levels. Obtain complete lipid profile after 9 to 12-hour fast. The reference values according to ATP III classification for making the diagnosis and risk stratification are depicted below:

Levels of total cholesterol (mg/dl)
< 200 Desirable
200 - 239 Borderline high
≥ 240 High
Levels of LDL cholesterol (mg/dl)
< 100 Optimal
100 - 129 Near optimal
130 - 159 Borderline high
160 - 189 High
≥ 190 Very high
Levels of HDL Cholesterol (mg/dl)
< 40 Low
≥ 60 High
Levels of serum triglycerides (mg/dl)
< 150 Normal
150 - 199 Borderline high
200 - 499 High
≥ 500 Very high

Other Laboratory Tests

For careful medical evaluation, must take into consideration all medications (both prescription and over-the-counter medications) and perform following tests to rule out secondary hyperlipidemias:

Other tests that may be done to have a definitive diagnosis include:

  • Studies of cells called fibroblasts (to see how the body absorbs LDL cholesterol)
  • Gene analysis or receptor analysis (to identify the specific defect associated with hyperlipidemia)

Many different types of mutations have been identified in the LDL-receptor (LDLR) gene. They have been categorized into four classes of alleles based on the phenotypic behavior of the mutant protein:

  • Class I - Null, in which LDL-receptor synthesis is defective.
  • Class II - Transport defect, in which intracellular transport from the endoplasmic reticulum to the Golgi apparatus is defective.
  • Class III - Binding defect, in which LDL-receptors are synthesized and transported to the cell surface normally, but binding of LDL-cholesterol is defective.
  • Class IV - Internalization defect, in which the LDL-receptors reach the cell surface and bind LDL-cholesterol normally, but LDL internalization is defective.

Approach

Shown below is a diagnostic algorithm to diagnose hyperlipidemia.[1]

 
 
 
 
 
 
 
 
Hyperlipidemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Triglycerides > 75th Percentile
 
 
NO
 
 
Type IIa
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
YES
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Types I, IIb, IV, V
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Total Cholesterol/Apo B ratio ≥ 6.2
 
 
NO
 
 
Types IIb, IV
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
YES
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Types I, III, V
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Triglycerides/Apo B ratio < 10.0
 
 
NO
 
 
Types I, V
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
YES
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Type III
 
 
 
 
 

References

  1. Sniderman A, Tremblay A, Bergeron J, Gagné C, Couture P (2007). "Diagnosis of type III hyperlipoproteinemia from plasma total cholesterol, triglyceride, and apolipoprotein B". Journal of Clinical Lipidology. 1 (4): 256–63. doi:10.1016/j.jacl.2007.07.006. PMID 21291689. Retrieved 2012-10-24. Unknown parameter |month= ignored (help)