I have a patient with nephrotic syndrome, renal vein thrombosis and two pulmonary embolisms in the last year. I told him that the nephrotic syndrome was likely due to membranous nephropathy and that all of his various blood clots are due to the kidney disease. The biopsy came back today and it is indeed membranous nephropathy.
Membranous nephropathy is a common finding when patients are biopsied for nephrotic syndrome. Fortunately, it is a relatively benign disease with a significant number of spontaneous remissions. (Schieppati, NEJM 1993)
Since there are so many spontaneous remissions and the therapy has significant side-effects we risk stratify patients in order to spare low-risk patients from treatment.
- older age (over 60) (Medline)
- male sex
- nephrotic range proteinuria
- greater than 8-10 g/day for more than 6 months (PDF)
- increased serum creatinine (Cr over 1.5) (Medline)
The biopsy findings have long been held of major importance on predicting prognosis but an analysis of 389 biopsies questioned whether histology provided information that independently predicted prognosis. (Medline)
Two urinary findings are gaining acceptance at being able to better predict the clinical course of disease. Beta-2 microglobulin excretion greater than 0.5 mcg/min and IgG excretion over 250 mg per day (others use the more sesitive value of 125 mg/24 hours) have both been associated with increased risk of renal progression. (Medline)
For patients with a low risk of progressing the recommendation is to stay and pray.
- Monitor the creatinine
- Institute non-specific antiproteinuric therapy (ACEi, ARB, aldosterone antagonists)
- Control the lipids
- Tight blood pressure control
- Day 1-3: 1 gram of methylprednisolone. This is usually done as an inpatient.
- Day 4-30: Oral prednisone, 0.5 mg/kg daily
- Day 31-60: Oral cyclophosphamide 2 mg/kg (chlorambucil in the original Ponticelli)
CJASN published an excellent review of membranous nephropathy (Medline).