SLE and idiopathic nephrotic syndrome: coincidence or not?

The association of systemic lupus erythematosus (SLE) with minimal change disease (MCD) and/or focal and segmental glomerulosclerosis (FSGS) has been described in isolated case reports. The relevance of this association is still debated.

We performed a retrospective and descriptive study of 11 patients with SLE who experienced idiopathic nephrotic syndrome (iNS) in an effort to determine the relevance of this unusual combination.

All patients fulfilled at least four criteria (renal abnormalities excluded) of the American Rheumatologic Association for the diagnosis of SLE, and all had severe nephrotic syndrome (mean proteinuria, 9.23 +/- 6 g of protein/24 h; serum albumin concentration, 1.48 +/- 0.6 g/dL). None had a past medical history of lupus nephritis or a cause for secondary FSGS. Renal histological examination showed MCD (4 patients) or FSGS (7 patients) without mesangial proliferation. Immunofluorescence was negative in 8 patients. In 3 patients, immune deposits (immunoglobulin G, immunoglobulin M, C3, and C1q) were present, but confined to the mesangium without glomerular changes on light microscopy. The abrupt onset of nephrotic syndrome coincided with the appearance of SLE in 6 patients (group 1) and recurrence of SLE in 3 patients (group 2). Two patients in group 1 experienced SLE recurrence with concomitant relapse of nephrotic syndrome. In only 2 patients (group 3) were the two diseases independent.

These results suggest that a relevant association exists between both diseases, and SLE could be a precipitating factor for iNS.