DECREASED URINARY APOLIPOPROTEIN (A) EXCRETION IN PATIENTS WITH IMPAIRED RENAL-FUNCTION

Background Plasma lipoprotein (a) [Lp(a)] levels are elevated in patie nts with kidney disease and are strongly associated with premature car diovascular disease and stroke. Methods As the kidney is suggested to play an important role in apolipoprotein (a) [apo(a)] catabolism and a s apo(a) fragments appear in urine, we determined plasma Lp(a) levels and urinary apo(a) excretion in relation to kidney function in a large cohort of renal patients. A total of 368 renal patients with normal o r different degrees of impaired renal function and 163 healthy control subjects matched for age and sex were investigated. Plasma Lp(a) and urinary apo(a) were analysed immunochemically. Results Renal patients were found to have significantly elevated total cholesterol and low-de nsity lipoprotein (LDL)-C values but lower high-density lipoprotein (H DL)-C values than control subjects. Plasma Lp(a) values were significa ntly higher only in patients with creatinine clearance <70 mL min(-1). There was a significant correlation between urinary apo(a) and plasma Lp(a) in patients and control subjects. Urinary apo(a) excretion was significantly lower in patients than in control subjects and showed no correlation with urinary protein excretion. Conclusion Although it is unlikely that impaired renal excretion of apo(a) fragments largely co ntributes to increased plasma LF(a) levels in patients suffering from impaired kidney function, these data suggest that urinary apo(a) excre tion is significantly decreased in renal patients and that this might contribute to increased plasma Lp(a) levels in this patient group.