A clinicopathologic study of thrombotic microangiopathy in IgA nephropathy

J Am Soc Nephrol. 2012 Jan;23(1):137-48. doi: 10.1681/ASN.2010111130. Epub 2011 Nov 3.


Thrombotic microangiopathy (TMA) occurs in IgA nephropathy, but its clinical significance is not well described. We retrospectively examined a series of 128 patients diagnosed with IgA nephropathy between 2002 and 2008 who had a mean follow-up of 44±27 months. In our series, 53% presented with lesions of TMA, acute or organized, in arteries and/or arterioles. Among patients with TMA, 4% were normotensive, 25% had controlled hypertension, and 71% had uncontrolled hypertension. Of those with uncontrolled hypertension, 26% had malignant hypertension. Histologically, the group with TMA had a significantly greater percentage of sclerotic glomeruli and worse tubulointerstitial fibrosis than those of the group without TMA. However, a significant minority of patients had near-normal histology, with minimal tubular atrophy (20%) and/or <20% interstitial fibrosis (24%). TMA rarely occurred in the absence of significant proteinuria. During follow-up, a doubling of serum creatinine or ESRD occurred in all patients with laboratory evidence of TMA, in 42% of those with morphologic evidence but no laboratory evidence of TMA, and in 11% of those without TMA. In summary, lesions of TMA are frequent in IgA nephropathy and may occur in normotensive patients with near-normal renal histology. Although the pathophysiologic mechanisms involved remain undetermined, the current study rules out severe hypertension or advanced renal disease as sole causes.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Blood Vessels / pathology*
  • Female
  • France / epidemiology
  • Glomerulonephritis, IGA / complications
  • Glomerulonephritis, IGA / epidemiology*
  • Glomerulonephritis, IGA / pathology
  • Humans
  • Hypertension / complications
  • Immunohistochemistry
  • Kidney / pathology*
  • Male
  • Middle Aged
  • Prevalence
  • Retrospective Studies
  • Thrombotic Microangiopathies / epidemiology*
  • Thrombotic Microangiopathies / etiology
  • Thrombotic Microangiopathies / pathology
  • Young Adult