Thrombotic microangiopathy in lupus nephritis patients

Objective: The aim of the present study was to evaluate the impact of thrombotic microangiopathy (TMA) on renal involvement in patients with lupus nephritis (LN). Patients and methods: This study included 50 systemic lupus erythematosus patients with LN who had been referred for renal biopsy. Patients underwent clinical and laboratory assessment for disease activity and damage. The biopsy specimens were classified according to the International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification, activity and chronicity indices, and assessed for renal TMA lesions. Results: TMA was found in 7/50 LN patients (14%). Patients with TMA lesions had significantly higher systolic and diastolic blood pressure (P = 0.018 and 0.019, respectively), higher serum creatinine (P = 0.031), lower estimated glomerular filtration rate (P = 0.023) and higher consumption of C3 (P = 0.002) than that of those without TMA lesions. Lupus anticoagulant positivity was significantly more frequent in patients with TMA (P = 0.001). There was a significant association between the detection of TMA and LN class IV. LN patients with TMA had significantly higher renal activity indices (P = 0.022). Chronicity index was higher in patients with TMA, but it did not reach a statistical significance. Conclusion: TMA is not an uncommon vascular change in patients with LN, especially in those with diffuse proliferative glomerulonephritis (class IV LN). It is associated with lupus anticoagulant positivity, C3 hypocomplentemia and higher renal biopsy activity index. TMA was significantly associated with renal impairment and systemic hypertension. Thus, TMA may be an important cause of renal injury and renal dysfunction in a subset of patients with LN, a histological entity associated with worse renal prognosis.