Serum lipoprotein(a) as an independent cardiovascular risk factor for patients undergoing chronic hemodialysis

Lipoprotein (a) Levels in Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

Most researchers have found increases of lipoprotein (a) [Lp(a)] in uremic patients, as well as in those undergo ng hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). The mechanisms for this increase remain unclear. We studied 71 patients undergoing CAPD, 48 me n and 23 women. According to the time spent on CAPD, the patients were divided into three groups: group 0: 29 patients at the starting off point of dialysis treatment; group I: 22 patients with an average stay of 15.2 months; group II: 20 patients with an average stay of 69.3 months on CAPD. We have only observed significant increases of Lp(a) levels in those patients initiating the dialysis, but no significant differences are found in the other groups undergoing CAPD for longer periods when compared to the control group. We found no significant relation between Lp(a) levels and peritoneal protein loss, and not with absorption of glucose from the dialysate either. We have found a positive and significant correlation between Lp(a) levels and urinary protein loss (r = 0.41; p < 0.001). It is possible that an element associated with proteinuria might have an effect on the metabolism of Lp(a) in CAPD patients.

Concentration of Lp(a) and other apolipoproteins in predialysis, hemodialysis, chronic ambulatory peritoneal dialysis and post-transplant patients

Serum levels of lipids, lipoprotein(a) Lp(a) and other apolipoproteins were determined in 47 predialysis patients, 40 hemodialysis (HD) patients, 39 chronic ambulatory peritoneal dialysis (CAPD) patients, 11 patients after kidney transplantation and 47 healthy subjects as reference group. The predialysis, HD, and CAPD patients had disturbances in the concentration of serum triglyceride (TG), high density lipoprotein (HDL)-cholesterol, apolipoprotein AI (apoAI), total apoCIII, apoCIII present in the particles without apoB (apoCIII non B), and Lp(a) and HDL-cholesterol, low density lipoprotein (LDL)-cholesterol/HDL-cholesterol, HDL-cholesterol/apoAI, apoAI/apoB, and apoAI/apoCIII ratios. Predialysis patients had significantly lower concentrations of HDL-cholesterol and total apoE levels than CAPD patients and total apoE level than HD patients. Moreover, both HD and CAPD patients had significantly increased levels of apoB containing apoE (apoB:E) and apoB containing apoCIII (apoB:CIII). The concentrations of serum TG, total cholesterol, LDL-cholesterol, apoB, Lp(a) in CAPD patients were statistically higher than in HD patients. The patients after transplantation demonstrated normalization of lipid and lipoprotein parameters and lipoprotein ratios except serum levels of TG, total apoCIII, apoCIII non B and the apoAI/apoCIII ratio. We concluded that abnormal lipid and lipoprotein concentrations in patients with uremia may be the cause of their high risk of atherosclerosis, but posttransplant patients exhibited improved levels of serum lipids, Lp(a) and other lipoprotein parameters and lipoprotein composition, which could be an index of decreased atherogenic status.

Early elevation of lipoprotein(a) levels in chronic renal insufficiency

Serum lipoprotein(a) [Lp(a)] concentrations in chronic renal failure patients were investigated in relation to the degree of renal insufficiency, treatment by maintenance hemodialysis, and correction of uremia by renal transplantation with or without cyclosporin immunosuppression. Fast serum levels of Lp(a) (mg/100 mL) were determined in 34 chronic renal failure patients not in need of maintenance dialysis (16 with serum creatinine 2.0-4.0 mg/100 mL; 18 with serum creatinine higher than 4.0 mg/100 mL), 40 patients treated by hemodialysis, 55 successful renal transplant recipients (28 under cyclosporin treatment and 27 receiving no cyclosporin), and 34 healthy controls. Age and sex distributions were similar among groups. Pregnant women; non-White individuals; subjects with obesity, diabetes, nephrotic syndrome, and hepatic and thyroid diseases; and those treated with oral contraceptives or lipid-lowering drugs were excluded from the study. Compared to controls, median Lp(a) was increased in nondialyzed renal failure patients (11 vs. 47.5 p < 0.001) and this was the only lipid abnormally observed in the group. There was no significant difference in Lp(a) levels between nondialized renal failure patients with serum creatinine 2.0-4.0 and > 4.0 mg/100 mL (47 vs. 49, NS). Moreover, Pearson correlation coefficient (r = 0.01, NS) showed that Lp(a) values were not related to serum creatinine in nondialyzed patients, In hemodialysis subjects Lp(a) concentrations (median = 29) were intermediate between those observed in nondialyzed patients and controls but the differences were not significant. Lp(a) levels in renal transplant patients treated with cyclosporin (median = 6) and not receiving cyclosporin (median = 13) were similar and did not differ from controls. Serum Lp(a) increases and attains maximum levels with mild/moderate reduction in renal function, and does not seem to change through late renal failure stages or in relation to the introduction of maintenance hemodialysis treatment. Correction of uremia by successful renal transplant caused normalization of Lp(a) levels regardless of the use of cyclosporin. Increased Lp(a) levels may be the earliest and more consistent lipid alteration seen in predialysis renal failure.