Antiphospholipid Syndrome and the Kidney.

The antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by a combination of arterial and/or venous thrombosis, pregnancy morbidity, and the persistent presence of circulating antiphospholipid antibodies (aPL). APS has been described as primary APS when it occurs in the absence of any features of other autoimmune disease, and as secondary in the presence of other autoimmune diseases, mainly systemic lupus erythematosus (SLE). There is a well-known link between SLE and APS; 40% of SLE patients have aPL, and, in turn, some, but only a minority of patients with APS, eventually will develop features of SLE. Because SLE and APS can target the kidneys independently or at the same time, discriminating between inflammatory or thrombotic lesions is crucial in planning therapy. We provide an overview of the renal manifestations associated with the presence of aPL in patients with SLE, and discuss the impact of aPL in selected scenarios such as lupus nephritis, end-stage renal disease, and pregnancy.