Background Mesangial lupus nephritis is considered benign with minimal potential for developing advanced chronic kidney disease (CKD). However, some patients still develop advanced CKD and end-stage renal disease (ESRD). Our objective was to describe the factors associated with the development of CKD stage IV or worse in patients with LN II.
Methods Patients with mesangial LN and ≥ 1 year follow-up were retrieved from the Toronto Lupus Clinic. Biopsy was performed because of proteinuria (n=55), rising serum creatinine (n=24), active urinary sediment (n=6) and generalized lupus activity (n=6). Patients with ESRD at baseline were excluded. Individuals were followed over time for the development of advanced CKD.
Results Of 91 eligible patients, 10 developed advanced CKD during follow-up, 7 CKD stage IV and 3 ESRD. Baseline characteristics in Table 1.
In 81/91 patients, there was no significant deterioration of the renal function after 16.8 years. Proteinuria was mild (1.17±0.89g). Fifteen patients had a repeat biopsy; histologic transformation was demonstrated in 10 (7 proliferative nephritis, 2 membranous, 1 advanced glomerulosclerosis). Sixty-three patients (67.7%) had normal renal function while 19.4% had CKD stage III (eGFR=30–59ml/min/1.73m2) at last visit.
Seven patients developed CKD IV (4 had impaired kidney function at baseline). Proteinuria was mild (<1g/day). Four had a repeat biopsy; 2 developed membranous nephropathy. Renal function remained stable (eGFR=24.2±4.3ml/min/1.73m2) after a mean of 18.5 years.
Three patients developed ESRD after 8.6, 10.3 and 16.8 years respectively. Two had a repeat biopsy demonstrating histologic transformation (proliferative nephritis, advanced glomerulosclerosis).
Conclusions Advanced CKD developed in 11% of LN II patients but the progression was slow. In most cases, kidney function was impaired at diagnosis while proteinuria was mild. These findings imply that mesangial disease can occasionally lead to CKD and underlines the need for close monitoring. Treatment should not be based on the level of proteinuria alone.
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