Informatii generale
HDL-colesterol (HDL-C) reprezinta un grup de lipoproteine sintetizate si secretate de hepatocite.
HDL detine un rol important in metabolismul colesterolului, participand la transportul acestuia din tesuturile extrahepatice catre ficat pentru catabolizare si excretie3.
Impreuna cu LDL-ul participa la mentinerea nivelului colesterolului celular.
Concentratiile HDL-colesterolului si apolipoproteinei-A sunt factori de risc pozitiv in ateroscleroza. Pacientii cu nivele ridicate ale HDL-C sunt protejati, avand un risc scazut de a face ateroscleroza9;12.
Nu s-a ajuns inca la un consens11 in privinta ierarhizarii celor doua teste: unii autori sugereaza superioritatea testarii APO A-I10, in timp ce altii recomanda HDL-colesterol6 pentru a aprecia mai fidel riscul de a dezvolta ateroscleroza.
Recomandari pentru determinarea colesterolului HDL
- evaluarea riscului de boala coronariana;
- diagnosticul hiperlipoproteinemiilor4;7.
Pregatire pacient
- pacientul sa respecte o dieta neschimbata timp de 3 saptamani inainte de recoltare;
- sa aiba o greutate corporala stabila;
- sa nu manance 12-14 ore inainte de recoltare (poate sa bea apa si cafea neagra fara zahar);
- se recomanda abstinenta de la alcool timp 72 de ore inainte de recoltare4;8.
Specimen recoltat – sange venos8.
Recipient de recoltare – vacutainer fara anticoagulant cu/fara gel separator8.
Prelucrare necesara dupa recoltare – se separa serul prin centrifugare; se lucreaza in aceeasi zi sau se stocheaza la 4ºC ori la -20ºC8.
Volum proba – minim 0.5 mL ser8.
Cauze de respingere a probei – specimen intens hemolizat8
Stabilitate proba – serul separat este stabil 5-7 zile la 2 -8°C; 3 luni la -20ºC; cativa ani la -70ºC8.
Metoda – spectrofotometrica (enzimatica)8.
Valori de referinta2
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Interpretare
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Valori (mg/dL)
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Normal
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>40
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Factor protector
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>60
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Raport colesterol total/HDL7:
Risc scazut: 3.3-4.4
Risc mediu: 4.4-7.1
Risc moderat: 7.1-11
Risc crescut: >11
Factor de conversie: mg/dL x 0.026= mmol/L
mmol/L x 38.66= mg/dL
Limita de detectie – 0.08 mmol/ (3 mg/dL)8.
Valori de alerta clinica – < 40 mg/dl se asociaza cu risc crescut de boala coronariana4.
Interpretarea rezultatelor
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Cresteri HDL-C
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Scaderi HDL-C
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• hiperalfalipoproteinemie (exces de HDL) familiala (autosomal dominanta)/secundara (alcoolism, pesticide, estrogeni),
• hipobetalipoproteinemie,
• clearance crescut al trigliceridelor,
• hepatopatie cronica, 4;7
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• hipoalfalipoproteinemie familiala (boala Tangier), • deficit de APO A-I si APO C-III, • hipertrigliceridemie familiala, • afectiuni hepatocelulare, • colestaza, • afectare renala cronica, uremie, sindrom nefrotic, • anemii si boli mieloproliferative cronice, • diabet zaharat, • hipo si hipertiroidism,• boala Niemann-Pick fara neuropatie4;7.
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Limite si interferente
Variatii intraindividuale: 3.6-12.4%7.
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Cresteri
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Scaderi
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• efort fizic intens si de durata, • consum moderat de alcool, • tratament cu insulina4;7;
• medicamente: cimetidina, ciclofenil, contraceptive orale, doxazosin, estrogeni, derivati ai acidului fibric (clofibrat, gemfibrozil), lovastatin, pravastatin, simvastatin, acid nicotic, fenobarbital, fenitoin, prazosin, terazosin, terbutalin, captopril, carbamazepine, coenzima Q10, furosemid, insulina, ketoconazol, medroxiprogesteron, niacin, nifedipina, verapamil etc.1;5;12;
• interferente analitice: cresterea concentratiei imunoglobulinelor determina o falsa crestere a HDL8.
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• inanitie si anorexie, • fumat, • stres si boala recenta (IMA, AVC, interventii chirurgicale, traumatisme), • obezitate, • lipsa antrenamentului fizic, • hipertrigliceridemie4;7;
• medicamente: androgeni, betablocante
(mai ales noncardioselective), acid
chenodeoxicolic, ciclosporina A,
ciproteron acetat (doze mari),
danazol, diuretice, etretinat,
interferon, interleukina, isotretinoin,
medroxiprogesteron, probucol,
progestative, tiazide5;12.
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Bibliografie
1. Betteridge DJ. High Density Lipoprotein and Coronary Heart Disease. In BMJ 298(6679): 974-5. 1989. Ref Type: Journal (Full).
2. Cleeman JI. Executive Summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evalution and Treatment of High Blood Cholesterol in Adults. In JAMA 285: 2486-97. 2001. Ref Type: Journal (Full).
3. Elena Popa Cristea. Metabolismul lipidelor. In Biochimie Medicala. Veronica Dinu, Eugen Trutia, Elena Popa-Cristea, Aurora Popescu, Editura Medicala, Romania, 2 ed., 1998, 394-478.
4. Frances Fischbach. Chemistry Studies. In A Manual of Laboratory and Diagnostic Tests. Lippincott Williams & Wilkins, USA, 8 ed., 2009, 450-452.
5. Frances Fischbach. Effects of Drugs on Laboratory Tests. In A Manual of Laboratory and Diagnostic Tests. Lippincott Williams & Wilkins, USA, 7 ed., 2004, 1243.
6. Gordon DJ, Rifkind BM. High Density Lipoprotein-the Clinical Implications of recent studies. In N Engl J Med 321(19): 1311-6. 1989. Ref Type: Journal (Full).
7. Jacques Wallach. Boli metabolice si ereditare. In Interpretarea testelor de diagnostic. Editura Stiintelor Medicale, Romania, 7 ed., 2001, 653-752.
8. Laborator Synevo. Referintele specifice tehnologiei de lucru utilizate 2010. Ref Type: Catalog.
9. Laboratory Corporation of America. Directory of Services and Interpretive Guide. High-Density Lipoprotein Cholesterol. www.labcorp.com 2010. Ref Type: Internet Communication.
10. Maciejko JJ, Holmes DR, Kottke BA, et al. Apolipoprotein A-1 as a Marker of Angiographically Assessed Coronary-Artery Disease. In N Engl J Med 309(7): 385-9. 1983. Ref Type: Journal (Full).
11. Miller NE. Association of High Density Lipoprotein Subclasses and Apolipoproteins with Ischemic Heart Disease and Coronary Atherosclerosis. In Am Heart J 113(2 ): 587-97. 1987. Ref Type: Journal (Full).
12. Peter P Toth. The “Good Cholesterol”, High-density Lipoprotein. In Circulation 111: 89-91. 2005. Ref Type: Journal (Full).
