Dyslipidemia is common among patients with end-stage renal disease, whether treated by hemodialysis (HD) or peritoneal dialysis (PD). To better understand the specific lipoprotein abnormalities in PD patients, we measured the lipid and apolipoprotein (Apo) composition of the four major classes of plasma lipoproteins in PD patients, HD patients, and healthy control subjects: very low density (VLDL), intermediate density (IDL), low density (LDL), and high density lipoproteins (HDL).
Fasting plasma samples were obtained from 15 nondiabetic PD patients, 15 nondiabetic HD patients, and 16 healthy control subjects, all from a cross section of patients and subjects in the region of Göteborg, Sweden. Lipoproteins were isolated by preparative ultracentrifugation, and lipid and apolipoprotein concentrations were measured by gas chromatography and electroimmunoassay, respectively.
Alterations in lipoprotein composition were apparent in all four lipoprotein density classes from PD and HD patients. VLDL contained a significantly higher concentration of ApoCIII in both HD and PD patients, and an elevation of free cholesterol, triglyceride, ApoB, ApoCII, and ApoE in PD patients. IDL from both PD and HD patients contained an excess of free and esterified cholesterol and triglyceride and significantly elevated levels of ApoB, ApoCII, ApoCIII, and ApoE. LDL had a higher concentration of ApoB in PD patients and elevated triglyceride and ApoCIII in both PD and HD patients. HDL isolated from PD patients had lower free cholesterol and ApoAI levels compared to control subjects, but these were not significantly different from HD patients.
An increase in lipid and apolipoprotein mass in IDL, and an enrichment of ApoCIII in VLDL, IDL, and LDL were observed in both HD and PD patients. The predominant alteration in lipoprotein composition distinguishing PD patients from HD patients was an elevation of ApoB in LDL. Further study of these alterations in lipoprotein composition in PD patients will be helpful in understanding the underlying causes of dyslipidemia and, ultimately, to the selection of hypolipidemic drugs or other treatments to reduce the cardiovascular risks associated with dyslipidemia in these patients.