Background: Lipoprotein X (LpX) is an abnormal lipoprotein fraction, which can be detected in patients with severe hypercholesterolaemia and cholestatic liver disease. LpX is composed largely of phospholipid and free cholesterol, with small amounts of triglyceride, cholesteryl ester and protein. There are no widely available methods for direct measurement of LpX in routine laboratory practice. We present the heterogeneity of clinical and laboratory manifestations of the presence of LpX, a phenomenon which hinders LpX detection.
Methods: The study was conducted on a 26-year-old female after liver transplantation (LTx) with severely elevated total cholesterol (TC) of 38 mmol/L and increased cholestatic liver enzymes. TC, free cholesterol (FC), cholesteryl esters (CE), triglycerides, phospholipids, HDL-C, LDL-C, and apolipoproteins AI and B were measured. TC/apoB and FC:CE ratios were calculated. Lipoprotein electrophoresis was performed using a commercially available kit and laboratory-prepared agarose gel.
Results: Commercially available electrophoresis failed to demonstrate the presence of LpX. Laboratory-prepared gel clearly revealed the presence of lipoproteins with γ mobility, characteristic of LpX. The TC/apoB ratio was elevated and the CE level was reduced, confirming the presence of LpX. Regular lipoprotein apheresis was applied as the method of choice in LpX disease and a bridge to reLTx due to chronic liver insufficiency.
Conclusions: The detection of LpX is crucial as it may influence the method of treatment. As routinely available biochemical laboratory tests do not always indicate the presence of LpX, in severe hypercholesterolaemia with cholestasis, any discrepancy between electrophoresis and biochemical tests should raise suspicions of LpX disease.
Uvod: Lipoprotein X (LpX) je patološka frakcija lipoproteina koja se može naći kod pacijenata sa teškom hiperholesterolemijom i holestatskih oboljenja jetre. LpX se uglavnom sastoji od fosfolipida i slobodnog holesterola, sa malim količinama triglicerida, estara holesterola i proteina. Ne postoje metode za direktno merenje LpX u rutinskoj laboratorijskoj praksi. Ovde je prikazana heterogenost kliničkih i laboratortijskih manifestacija prisustva LpX, fenomena koji ometaju otkrivanje LpX.
Metode: Izučavanje je izvedeno na 26-godišnjoj ženi posle transplantacije jetre (LTx) sa izrazito povećanim ukupnim holesterolom (TC) vrednosti 38 mmol/L i holestatskim jetrenim enzimima, a mereni su i TC, slobodni holesterol (FC), holesteril estri (CE), trigliceridi, fosfolipidi, HDL-C, LDLC i apolipoproteini AI i B. Izračunati su odnosi TC/apoB i FC:CE. Izvedena je elektroforeza apolipoproteina primenom komercijalnog kita i agaroza gela koji je pripremljen u laboratoriji.
Rezultati: Komercijalnom elektroforezom nije bilo moguće utvrditi prisustvo LpX. Primenom laboratorijski pripremljenog gela utvrđeno je prisustvo lipoproteina čija je pokretljivost odgovarala LpX. Odnos TC/apo B je bio povećan, a nivo CE snižen, što je potvrdilo prisustvo LpX. Lipoproteinska afereza je primenjena kao metoda izbora za oboljenja sa LpX i vezu sa relLTx usled hronične insuficijencije jetre.
Zaključak: Za otkrivanje LpX veoma je važan izbor metode. S obzirom da rutinski raspoloživi biohemijski laboratorijski testovi uvek ne ukazuju na prisustvo LpX u teške hiperholesterolemije sa holestazom, bilo koja razlika između eketroforeze i biohemijskih testova treba da ukaže na sumnju da postoji LpX oboljenje.
Keywords: cholestasis; electrophoresis; hepatobiliary disorders; lipoprotein X; severe hypercholesterolaemia.
2020 Agnieszka Ćwiklińska, Agnieszka Mickiewicz, Robert Kowalski, Barbara Kortas-Stempak, Agnieszka Kuchta, Krzysztof Mucha, Michał Makowiecki, Anna Gliwińska, Krzysztof Lewandowski, Leszek Pączek, Marcin Fijałkowski, Marcin Gruchała, Maciej Jankowski, published by CEON/CEES.