Detection of serum and urinary lipoprotein(a) in patients with renal diseases

We measured and analysed serum and urinary lipoprotein(a) [Lp(a)] in 73 patients with various renal diseases, and 168 control subjects. The results revealed that serum Lp(a) levels were significantly elevated in patients with mesangial proliferative glomerulonephritis, membranous nephropathy, chronic renal failure and diabetic nephropathy, except patients with IgA nephropathy (IgAN) with gross haematuria. Serum Lp(a) concentrations were found to be significantly correlated with serum albumin ( r =−0.5033, P <0.001) and urinary protein excretion ( r =0.3541, P <0.005), while not with serum creatinine ( r =−0.0144, P >0.05). Patients with selective urinary protein excretion had a lower serum Lp(a) level than those with non-selective urinary protein excretion. The correlation between serum albumin and serum Lp(a) levels remained significant ( P <0.001) after adjustment for serum creatinine, urinary protein excretion and the selectivity of urinary protein by multivariate regression analysis. Urinary Lp(a) excretion was decreased and related to the serum creatinine level ( r =−0.312, P <0.01). Our conclusion is that renal patients with proteinuria and hypoalbuminemia tend to have elevated levels of Lp(a) which are more significantly correlated to serum albumin levels than other parameters such as serum 24-h urinary protein, selectivity of urinary protein and serum creatinine; while urinary Lp(a) excretion varies inversely with serum creatinine levels.