Kidney disease in antiphospholipid syndrome

The kidney is a major target organ in patients with the antiphospholipid syndrome (APS). However, it is only in the past few years that knowledge about renal vascular involvement in APS has acquired a critical mass. This can be explained because APS was first described in patients with systemic lupus erythematosus (SLE) and the studies were focused on the immune complex-mediated glomerulonephritis rather than the renal vascular lesions. In addition, the risks of a renal biopsy in APS patients because of the frequent occurrence of thrombocytopenia and systemic hypertension, discouraged the procedure and impeded the pathologic demonstration of intrarenal thrombotic lesions. The renal manifestations may result from thrombosis occurring at any location within the renal vasculature, including large vessels, both arterial and venous, the intraparenchymatous arteries and arterioles, as well as the glomerular capillaries. However, other types of renal involvement including membranous glornerulonephritis, pauci-immune crescentic glomerulonephritis, IgA nephropathy, focal segmental glomerulosclerosis, glomerulonephritis with isolated C3 mesangial deposits, and vasculitis associated with aPL have all been described. It is unclear whether, in addition to thrombosis, other mechanisms could also contribute to the pathogenesis of the nephropathy of APS (NAPS). The consequences of the renal compromise include renovascular hypertension, renal infarcts, cortical atrophy, acute renal failure, proteinuria, and end stage renal disease (Table 1). There is a prevailing opinion that given its importance and unique features, the NAPS, should be included in the APS classification criteria. In this review, I will discuss systemic hypertension, renal artery lesions, the NAPS, renal vein thrombosis, the significance of antiphospholipid antibodies (aPL) in patients with SLE, and the relevance of aPL in end stage renal failure and renal transplantation. [GRAPHICS] NAPS, renal vein thrombosis, the significance of antiphospholipid antibodies (aPL) in patients with SLE, and the relevance of aPL in end stage renal failure and renal transplantation.