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This Article Full Text Full Text (PDF) All Versions of this Article: CJN.01330209v1 4/9/1417    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Hladunewich, M. A. Articles by Cattran, D. C. PubMed PubMed Citation Articles by Hladunewich, M. A. Articles by Cattran, D. C.

The Natural History of the Non-Nephrotic Membranous Nephropathy Patient

University Health Network, University of Toronto, Toronto, Ontario, Canada

Address Correspondence to: Dr. Daniel C. Cattran, NCSB 11-1256, 585 University Avenue, Toronto, Ontario, Canada M5G 2N2. Phone: 416-340-4187; Fax: 416-340-3714; E-mail: daniel.cattran{at}uhn.on.ca

Background and objectives: Although early studies suggest that patients with idiopathic membranous nephropathy (MGN) and subnephrotic range proteinuria overall do well, these studies were small and follow-up was short or difficult to discern.

Design, setting, participants, & measurements: Three hundred ninety-five cases of idiopathic MGN with at least 12 mo of follow-up from the Toronto Glomerulonephritis Registry were reviewed to determine the outcome of the subgroup of patients that presented with subnephrotic range proteinuria. Onset and follow-up data included mean arterial pressure (MAP) and creatinine clearance (CrCl) as determined by the Cockcroft-Gault equation. Outcome variables included the rate of progression (slope of CrCl), 50% reduction in initial CrCl, and end-stage renal disease (ESRD).

Results: One hundred eight (27% of the total) patients presented with subnephrotic proteinuria and almost 40% (42 of 108) of this subgroup remained subnephrotic. Their long-term slope was –0.93 ml/min/yr. In contrast, those who subsequently developed nephrotic range proteinuria had a progression rate almost four times faster (–3.52 ml/min/yr). The majority who developed nephrotic syndrome did so within the first year of follow-up. The only distinguishing baseline feature between the two groups was a higher level of urine protein in the group that subsequently developed nephrotic syndrome (1.98 [0.3 to 3.4] versus 2.43 [0.5 to 3.4] g/d).

Conclusions: Patients with MGN and sustained subnephrotic range proteinuria have an excellent prognosis. Conservative management with close monitoring is recommended given the difficulty predicting which patients will develop nephrotic range proteinuria and then progress more rapidly.