OBJECTIVE To analyze the relationship between lipoprotein(a) [Lp(a)] and fibrinogen as potential cardiovascular risk factors in patients on continuous ambulatory peritoneal dialysis (CAPD). METHODS A total of 47 uremic patients receiving CAPD, 21 with coronary artery disease (CAD), 26 without CAD. METHODS Lp(a) levels were determined by an immunoradiometric assay. Since Lp(a) serum concentrations vary depending on the size, apoprotein(a) [apo(a)] isoforms were determined (Westernblot). Fibrinogen was quantified according to Clauss. RESULTS The mean Lp(a) serum concentration was 43 +/- 5 mg/dL (SEM) (median 33 mg/dL) in CAPD patients and 21 +/- 2 mg/dL (8 mg/dL) in controls (p < 0.01). Patients with low molecular weight apo(a) isoforms exhibited substantially elevated Lp(a) levels when compared with patients with high molecular isoforms (p < 0.01). In addition, we found elevated fibrinogen levels in the CAPD patients (538 +/- 61 mg/dL) compared with healthy controls (288 +/- 46 mg/dL). Twenty-one CAPD patients (45%) were suffering from CAD. Patients with CAD had higher Lp(a) levels (54 +/- 5 mg/dL vs 34 +/- 4 mg/dL) as well as higher fibrinogen concentrations (628 +/- 59 mg/dL vs 459 +/- 46 mg/dL). Furthermore, a positive correlation between the fibrinogen levels and the Lp(a) serum concentration was observed (r = 0.45, p = 0.01). CONCLUSIONS We suggest that elevated Lp(a) levels are influenced by the allelic variation of the apo(a) isoform. In addition to the typical dyslipidemia found in CAPD patients, high levels of Lp(a) and fibrinogen may contribute to the elevated risk of coronary artery disease and other cardiovascular complications.