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Objectives We aimed to explore the value of glomerular hematuria for the diagnosis of new-onset nephritis in patients with systemic lupus erythematosus (SLE).Methods Cross-sectional study of SLE patients who underwent a kidney biopsy due to suspicion for lupus nephritis (LN). Demographic, clinical, and serologic data at the time of biopsy were collected. Clinically significant LN was defined as ISN/RPS class III, IV, V, or mixed III/IV+V. Renal presentation patterns were categorized based on the presence of glomerular hematuria, proteinuria, and impaired kidney function. Among patients with glomerular hematuria, logistic regression analysis was performed to identify independent predictors of clinically significant LN. A nomogram was constructed for clinical application.Results Of 227 kidney biopsies in patients with SLE, 181 (79.7%) revealed clinically significant LN; the remaining had class II LN (4.4%) and focal segmental glomerulosclerosis (FSGS) (5.7%), among other diagnoses. Proliferative forms of LN predominated among patients with combined urinary abnormalities (defined as any combination of glomerular hematuria, proteinuria, and impaired kidney function (99/126, 78.6%), whereas class V LN presented mainly with isolated proteinuria (34/46, 73.9%). Isolated glomerular hematuria occurred in 11 (4.8%) patients. The majority of these cases (9/11, 81.8%) revealed non-LN pathology, and only 2 yielded LN (1 class II, 1 class III), both demonstrating concurrent SLE serologic activity with anti-dsDNA antibody positivity and low complement levels.Among patients with glomerular hematuria (n= 137), independent predictors of clinically significant LN included higher proteinuria (OR 3.77 per 1-gr of urine protein, 95% CI 2.00–9.03), anti-dsDNA positivity (OR 12.00, 3.36–51.40), higher non-renal SLEDAI score (OR 1.20 per 1-unit, 1.02–1.46), and younger age (OR 0.96 per 1-year, 0.91–1.00). The combined presence of these factors yielded a 97% (95% CI 90–99%) predicted probability of clinically significant LN, while their absence was associated with a markedly low probability (6%, 95% CI: 1-23%) (figure 1).Abstract PT2:04 Figure 1Additive effect of clinical and serological variables on the probability of clinically significant LN among SLE patients who present with glomerular hematuriaConclusions Isolated glomerular hematuria, in the absence of other risk factors, was infrequently associated with clinically significant LN in our study; when considering the need for a kidney biopsy, glomerular hematuria should be evaluated in the context of overall disease activity.