Cholesteryl Esters, Serum
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cholesterol in the blood serum normally is 60% to 80% esterified with fatty acids, largely as a result of the action of the enzyme lecithin-cholesterol acyltransferase (LCAT), which circulates in the blood in association with the high-density lipoproteins. LCAT transfers an acyl group for lecithin to cholesterol.
Familial deficiency of LCAT is uncommon, usually occurring individuals of northern Europe descent, and is associated with erythrocyte abnormalities (target cells) and decreased (20% or less) esterification of plasma cholesterol. This is associated with early atherosclerosis, corneal opacification, hyperlipidemia, and mild hemolytic anemia.
Persons with liver disease may have impaired formation of LCAT and, therefore, a secondary deficiency of this enzyme and of esterified plasma cholesterol.
Establishing a diagnosis of lecithin-cholesterol acyltransferase deficiency
Evaluating the extent of metabolic disturbance by bile stasis or liver disease
In patients with lecithin-cholesterol acyltransferase deficiency, the concentration of unesterified cholesterol in serum may increase 2 to 5 times the normal value, resulting in a decrease in esterified serum cholesterol to 20% or less of the total serum cholesterol.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Cholesteryl ester storage disease in a severe form can be fatal before the age of 1 year (Wolman's disease), and in some cases may be undetected until adulthood in less severe forms. This defect is caused by a deficiency of a lysosomal enzyme, acid cholesteryl ester hydrolase (also known as acid lipase). It causes accumulation of cholesteryl esters in tissues, but it has no effect on the percentage of cholesterol that circulates in esterified form in the blood serum. Detection of the defect requires careful evaluation of the cholesteryl ester hydrolase activity and cholesteryl ester content of leukocytes, cultured fibroblasts, and liver biopsy.
Result can be falsely decreased in patients with elevated levels of N-acetyl-p-benzoquinone imine (NAPQI)-a metabolite of acetaminophen, N-acetylcysteine (NAC), and metamizole.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
60-80% of total cholesterol
Reference values have not been established for patients that are <16 years of age.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
Glomset JA, Assmann G, Gjone E, Norum KR: Lecithin: cholesterol acyltransferase deficiency and fish eye disease. In The Metabolic Basis of Inherited Disease. Seventh edition. Edited by CR Scriver, AL Beaudet, WS Sly, D Valle. New York, McGraw-Hill Book Company, 1995, pp 1933-1951