Effect of increasing serum albumin on serum lipoprotein(a) concentration in patients receiving CAPD.

Lipoprotein(a) [Lp(a)], an independent risk factor for atherosclerotic cardiovascular disease in the general population, is known to be elevated in patients with renal disease accompanied by hypoalbuminemia such as nephrotic syndrome and end-stage renal disease. In this study, the role of hypoalbuminemia in the elevation of serum Lp(a) was investigated in 20 continuous ambulatory peritoneal dialysis (CAPD) patients with serum albumin below 3.5 g/dL. The patients were divided into two groups. In group 1 (n = 10), fasting serum Lp(a) and albumin were measured before, after repeated infusion of 20% albumin 100 mL three times per week for 2 weeks, and 4 weeks after withdrawal of albumin infusion. In group 2 (n = 10), serum albumin and Lp(a) were measured similarly without albumin infusion. C-reactive protein was monitored in both group as an indicator of acute-phase reactant. Serum Lp(a) was also measured in 20 age- and sex-matched normal controls. Apolipoprotein(a) [apo(a)] phenotype was determined in all the subjects. CAPD patients as a whole (n = 20; median, 70.2 mg/dL; interquartile range, 45.0 to 86.2 mg/dL) had higher serum Lp(a) than normal controls (n = 20; median, 9.9 mg/dL; interquartile range, 2.4 to 24.3 mg/dL) (P < 0.0001), although the distribution of apo(a) phenotype was similar. Serum albumin in group 1 increased from 2.6+/-0.5 g/dL to 3.5+/-0.6 g/dL (P < 0.0005) at the end of repeated infusion of albumin, whereas serum Lp(a) decreased from 73.7 mg/dL (range, 43.2 to 89.0 mg/dL) to 25.6 mg/dL (range, 10.7 to 71.7 mg/dL) (P < 0.01). Four weeks after withdrawal of albumin infusion, serum albumin decreased again to 2.9+/-0.5 g/dL (P < 0.001), whereas serum Lp(a) increased to 65.2 mg/dL (range, 43.3 to 106.0 mg/dL) (P < 0.05). Serum albumin in group 2 was 2.8+/-0.6 g/dL, 3.0+/-0.4 g/dL, and 2.9+/-0.7 g/dL, respectively. The change of serum Lp(a) was not significant (67.0 mg/dL [range, 46.8 to 84.8 mg/dL], 62.8 mg/dL [range, 45.1 to 81.0 mg/dL], and 63.0 mg/dL [range, 44.7 to 74.0 mg/dL]). C-reactive protein was stable during the study period in both groups. These findings support the hypothesis that hypoalbuminemia is one of the important trigger factors in the elevation of serum Lp(a) in CAPD patients.