Plasma total homocysteine concentration in nephrotic patients with idiopathic membranous nephrophathy

Background. The atherothrombotic risk pattern of the nephrotic syndrome res embles that of hyperhomocysteinemia. However, the effect of nephrotic range proteinuria on homocysteine metabolism has never been studied. Methods. The study included 11 male nephrotic patients with idiopathic memb ranous nephropathy who underwent a treatment trial with adrenocorticotrophi c hormone and 11 male non-nephrotic, renal function-matched control subject s. The nephrotic patients were studied before and after the treatment, whic h induced a marked reduction in urinary protein excretion and a moderate im provement in renal function in all cases. Results. Plasma total homocysteine (tHcy) concentration did not change sign ificantly during treatment, whereas the nephrotic patients had significantl y lower tHcy than the non-nephrotic patients (14.2 +/- 3.4 mu mol/l vs 19.0 +/- 5.4 mu mol/l). tHcy correlated significantly with serum concentrations of creatinine (r = 0.53, P < 0.05) and albumin (r = 0.43, P < 0.05), glome rular filtration rates (GFRs) (iohexol clearances) (r = -0.42, P < 0.05) an d urinary albumin excretion (r = -0.47, P < 0.05). Conclusion. The expected tHcy-lowering effect of improved renal function ma y have masked a tHcy-elevating effect due to reduced proteinuria leading to no net change in tHcy during treatment. The notion of an increase in tHcy associated with remission of the nephrotic syndrome is in accordance with t he significantly lower tHcy in the nephrotic renal patients compared with t he non-nephrotic renal function-matched patients, and the relationships bet ween tHcy and serum albumin concentrations as well as urinary albumin excre tion. Thus, the results of this small study suggest that nephrotic range pr oteinuria directs homocysteine metabolism towards a decrease in tHcy. Howev er, the findings need to be confirmed in larger patient populations and in different varieties of the nephrotic syndrome.