Definition
- Phospholipids are a class of lipids consisting of a hydrophilic polar head group and a hydrophobic tail. The polar head group contains one or more phosphate groups. The hydrophobic tail is made up of two fatty acyl chains. In an aqueous environment, the hydrophilic heads of the phospholipid molecules tend to face water and the hydrophobic tails bond together, forming a bilayer, which constitutes a major portion and function of cell membranes. Most of the phospholipids in human plasma are phosphatidyl choline (70 " 75%) or sphingomyelin (18 " 20%). The remaining phospholipids include phosphatidyl serine, phosphatidyl ethanolamine (3 " 6%), and lysophosphatidyl choline (4 " 9%).
- Normal range: 150 " 380 mg/dL.
Use
- Aids in the diagnosis of obstructive jaundice, Tangier disease, beta- or hypobetalipoproteinemia, and lecithin cholesterol acyltransferase deficiency.
- Phospholipid analysis rarely provides added beneficial information in cases of dyslipoproteinemia.
Interpretation
- Phospholipids are increased in hyperlipidemias and obstructive liver disease.
- They are decreased in Tangier disease.
Suggested Reading
1McPherson RA, Pincus MR. Lipids and dyslipoproteinemia (estimation of plasma lipids). In: McPherson RA, Pincus MR (eds.). Henrys Clinical Diagnosis and Management by Laboratory Methods, 21st ed. Philadelphia, PA: Saunders Elsevier: 2007:200 " 218.