Post Date December, 03 2023
Up to 75% of patients with systemic lupus erythematosus (SLE) may exhibit lupus nephritis (LN). The membranous LN (MLN, type V LN) defined by the International Association of Renal Pathology is less common than proliferative LN (PLN, type III and IV LN), and can be seen in approximately 10-20% of patients. Proliferative and membranous lesions can exist simultaneously or alone in the same patient.
Although MLN alone has a better prognosis than PLN, it is still associated with significant mortality, including the risk of thrombosis associated with severe hypoproteinemia, the risk of transition to PLN, and the risk of progression to end-stage renal disease (ESRD) after 10 years.
The optimal treatment strategy for MLN is unclear and typically includes immunosuppressive treatment for patients with proteinuria, reduced GFR, or coexistence of MLN/PLN in the range of nephrotic syndrome (NS). The level of evidence in the guidelines for MLN treatment developed by the Global Organization for Improving Renal Disease Outcome (KDIGO) is low.
Clinical manifestations of MLN
SLE patients are mostly young women. Although the clinical manifestations of LN patients are similar among different ages and sexes, men may be more likely to have a severe course of disease. Although proteinuria levels may be in the range of sub renal disease, patients with MLN typically exhibit the characteristics of NS. Microscopic examination of urinary sediment may reveal microscopic hematuria and red blood cell tubular patterns. Therefore, the presence of a red blood cell tubular type does not mean that it is a type III or IV LN, but the coexistence of MLN and PLN must be considered.
Anti nuclear antibody testing results are usually positive, but the positive variability of anti dsDNA antibodies is significant, and complement levels may be normal. Hypertension and decreased renal function may occur without proliferative lesions. It has been reported that LN is associated with a significantly increased incidence rate of ischemic heart disease.
Thrombosis and pulmonary embolism may be the clinical characteristics of MLN. Even if there is no thrombus present, patients with significantly elevated D-D dimers still have an increased risk of subsequent thrombotic events. However, more significant proteinuria and higher positive rates of anti phospholipid antibodies may also be confounding factors. D-D dimers have yet to be proven as a risk factor stratification or anticoagulation initiation tool.
Severe hypoproteinemia (Alb<2.8 g/dL) is clearly associated with an increased risk of thrombosis, especially in primary membranous nephropathy. In patients with SLE, antiphospholipid antibodies (especially lupus anticoagulants and β 2-Glycoprotein 1 IgG antibody) is associated with a higher incidence of arterial and/or venous thrombosis. The simultaneous presence of antiphospholipid antibodies and hypoproteinemia is likely to increase the risk of thrombotic disease and lower the threshold for initiating anticoagulation therapy.
