Significant kidney disease may be present in patients with systemic lupus erythematosus (SLE) despite low-level proteinuria, according to study findings published in Kidney International Reports.
American College of Rheumatology guidelines recommend performing a kidney biopsy in patients with SLE who have proteinuria of at least 1000 mg/24 hours. To evaluate the relevance of this cutoff, investigators identified 87 patients with proteinuria below 1000 mg/24 hours. Of these, 52 (60%) had isolated low-level proteinuria (no acute kidney injury or active urinary sediment), Alice Chedid, MD, of the University of Tennessee Health Science Center in Memphis, Tennessee, and colleagues reported.
Histologic evidence of lupus nephritis (LN) was present in 40 (76%) of the 52 patients. This group included 12 patients with class 1 or 2, 14 with class 3 or 4, and 8 with class 5 LN, and 6 with combined proliferative and membranous LN. Laboratory abnormalities did not predict the presence of LN.
In the 12 patients with non-LN kidney disease, diagnoses included focal segmental glomerulosclerosis, acute interstitial nephritis, immune complex-mediated glomerulonephritis, and diabetic nephropathy, among others.
The authors said their results add to a growing body of evidence showing that a relevant proportion of patients with SLE who have isolated low-level proteinuria have proliferative LN, which warrants treatment with immunosuppressive agents, or membranous LN, which requires at least close monitoring.
“These results suggest that it might be time to rethink current SLE recommendations and expand indications for kidney biopsy to include patients with SLE with isolated low-level proteinuria of any grade, as supported by our series,” they concluded.
Chedid A, Rossi GM, Peyronel F, et al. Low-level proteinuria in systemic lupus erythematosus. Kidney Int Rep. 2020;5:2333-2340. doi:10.1016/j.ekir.2020.09.007