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Test ID: LCATD    
Lecithin Cholesterol Acyltransferase Deficiency Profile

Useful For Suggests clinical disorders or settings where the test may be helpful

Detection of lecithin cholesterol acyltransferase deficiency

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Lecithin cholesterol acyltransferase (LCAT) catalyzes the esterification of free cholesterol in plasma lipoproteins. LCAT is critical for HDL metabolism and reverse cholesterol transport.(1) LCAT transfers fatty acid from phosphatidylcholine to cholesterol creating lysophosphatidylcholine (LPC) and cholesteryl ester. LCAT deficiency leads to increased plasma concentrations of phosphatidylcholine and free cholesterol, concurrent with reduced concentrations of LPC and cholesteryl esters.

 

Familial LCAT deficiency and fish-eye disease are 2 inherited disorders of LCAT deficiency. Both syndromes are characterized by corneal opacities secondary to accumulation of free cholesterol and phospholipids.(2-3) Acquired LCAT deficiencies have been reported in association with nephrotic syndrome.(4) Regardless of etiology, LCAT deficiency leads to markedly decreased or entirely absent HDL cholesterol and normal to elevated triglycerides. Low HDL cholesterol and high triglycerides are commonly associated with increased risk of cardiovascular disease (CVD). However, to date, studies designed to address the association between LCAT activity and CVD have been inconclusive.

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.

CHOLESTEROL, TOTAL

The National Cholesterol Education Program (NCEP) has set the following guidelines (reference values):

Desirable: <200 mg/dL

Borderline high: 200-239 mg/dL

High: > or =240 mg/dL

 

The Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents has set the following guidelines in children 2 to 17 years of age:

TOTAL CHOLESTEROL

Acceptable: <170 mg/dL

Borderline high: 170-199 mg/dL

High: > or =200 mg/dL

 

CHOLESTERYL ESTERS

> or =16 years of age: 60-80% of total cholesterol

Reference values have not been established for patients that are <16 years of age.

 

PHOSPHOLIPIDS

> or =16 years of age: 155-275 mg/dL

Reference values have not been established for patients that are <16 years of age.

 

LYSOPHOSPHATIDYLCHOLINE

> or =16 years of age:

16:0 Lysophosphatidylcholine: > or =62 mcmol/L

18:0 Lysophosphatidylcholine: > or =20 mcmol/L

Reference values have not been established for patients that are <16 years of age.

Interpretation Provides information to assist in interpretation of the test results

Norum-Gjone disease is a severe form of lecithin cholesterol acyltransferase (LCAT) deficiency characterized by:

-Diminished serum levels of cholesterol ester (<50%)

-Increased serum levels of nonesterified cholesterol

-Increased serum levels of phospholipids

-Decreased concentration of lysophosphatidylcholine

-Decreased high-density lipoproteins (HDL)

-Increased triglycerides

 

Fish-eye disease, a less severe form of LCAT deficiency, generally demonstrates less severe changes in the parameters that are measured. Fish-eye disease appears to be specifically associated with esterification of HDL cholesterol.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

If lecithin cholesterol acyltransferase (LCAT) deficiency is suspected from initial tests, analysis of triglycerides and HDL cholesterol will be performed at no charge. If fish-eye disease is suspected, percent cholesterol ester in the HDL fraction will be measured.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Kunnen S, Van Eck M: Lecithin:cholesterol acyltransferase: old friend or foe in atherosclerosis? J Lipid Res 2012;53:1783-1799

2. Norum KR, Gjone E: Familial serum-cholesterol esterification failure. A new inborn error of metabolism. Biochim Biophys Acta 1967;144:698-700

3. Carlson LA, Philipson B: Fish-eye disease. A new familial condition with massive corneal opacities and dyslipoproteinaemia. Lancet 1979;2:922-924

4. Calabresi L, Simonelli S, Conca P, et al: Acquired lecithin:cholesterol acyltransferase deficiency as a major factor in lowering plasma HDL levels in chronic kidney disease. J Intern Med 2014 DOI: 10.1111/joim.12290

5. Holleboom AG, Kuivenhoven JA, Vergeer M, et al: Plasma levels of lechithin:cholesterol acyltransferase and risk of future coronary artery disease in apparently healthy men and women: a prospective case-control analysis nested in the EPIC-Norfolk population study. J lipid Res 2010;51:416-421

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test