Thrombotic microangiopathy in IgA nephropathy; new evidence and ideas

The Oxford classification for IgA nephropathy (IgAN) does not currently include thrombotic microangiopathy (TMA) as a parameter, despite evidence that TMA can occur in IgAN patients and impact outcomes. Prior studies have found that a significant proportion of IgAN patients have histological evidence of TMA, either acute or organized, in their renal biopsies. Moreover, patients with TMA lesions in IgAN tend to have worse outcomes, including a greater percentage of sclerotic glomeruli, more tubulointerstitial fibrosis, and higher rates of doubling of serum creatinine or progression to end-stage renal disease compared to IgAN patients without TMA. Other researchers have suggested that TMA in IgAN is commonly located in the advanced steps of the disease and may be accompanying by severe hypertension and proteinuria. However, the Oxford system does not include TMA as a parameter. Therefore, further investigations are required to determine the clinical significance and optimal management of TMA in IgAN individuals. Renal arteriolar microangiopathic lesions can occur in immunoglobulin A nephropathy, but their role in disease progression has been unclear. Furthermore, the main limitation of the MEST-C classification is that it does not currently account for the presence and impact of TMA in IgAN, despite evidence that TMA is a common and clinically relevant histological finding in these patients.