|Values are valid only on day of printing.|
The phospholipids comprise about 1/3 of the total lipids in serum. These consist in a large part of a lipid, phosphatidylcholine (formerly lecithin), in which 1 of the glycerol carbons is esterified with choline phosphate. A major step in lipoprotein particle remodeling results from lecithin-cholesterol acyltransferase (LCAT) activity, which normally transesterifies free cholesterol with fatty acids derived from phosphatidylcholine. LCAT deficiency results in a lack of remodeling of primary lipoprotein particles, affecting eventual cholesterol uptake and elimination. In cases of deficiency of LCAT, the concentration of lecithin in the serum are increased several-fold.
Clinical findings in LCAT deficiency include corneal opacities, anemia, and frequently, proteinuria. The disorder is inherited as an autosomal recessive trait. Early atherosclerosis develops in many individuals with this disorder.
In addition, sphingomyelin normally comprises about 5% to 20% of the total phospholipids of serum. In Niemann-Pick Type A and B diseases, sphingomyelin accumulates in visceral and neural tissues and may become increased in the serum.
Other disorders involving alterations of the concentration, composition, and/or lipoprotein distribution include: abeta- or hypobetalipoproteinemia, Tangier disease, or fish eye disease.
First-order test in the diagnosis of lecithin-cholesterol acyltransferase deficiency
Elevated in cases of lecithin-cholesterol acyltransferase deficiency deficiency due to elevations of lecithin
Analyses of disorders mentioned are complex. Specialized additional testing may be required.
Reference values have not been established for patients who are <16 years of age.
1. Baehorik PS, Levy RI, Rifkind BM: Lipids and dyslipoproteinemia. In Clinical Diagnosis and Management by Laboratory Methods. 18th Edition. Edited by JB Henry. Philadelphia, WB Saunders Company, 1991, p 198
2. Norum KR, Gjone E, Glomset JA: Familial lecithin: cholesterol acyltransferase deficiency, including fish eye disease. In The Metabolic Basis of Inherited Disease. Sixth Edition. Edited by CR Scriver, AL Beaudet, WS Sly, D Valle. New York, McGraw-Hill Book Company, 1989, pp 1181-1194