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Kidney Week

Abstract: PO1850

Does Kidney Histology Predict Renal Response or Complement Status in Atypical Hemolytic Uremic Syndrome?

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Carter, Jessamyn S., The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Sukumar, Senthil, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Yildiz, Vedat O., The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Cassol, Clarissa Araujo, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Brodsky, Sergey V., The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Nadasdy, Tibor, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Cataland, Spero R., The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
  • Parikh, Samir V., The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
Background

Atypical Hemolytic Uremic Syndrome (aHUS) is diagnosed based on clinical evidence of microangiopathic hemolytic anemia, thrombocytopenia and renal failure and histologic evidence of thrombotic microangiopathy (TMA). However, these characteristics are not specific and cannot differentiate aHUS from other causes. Whether specific histologic lesions of TMA can predict complement mutation status (CM +/-), guide treatment, or predict renal outcomes has not been explored. Here, we evaluate the potential of using kidney histology to predict CM status and renal response in aHUS.

Methods

A retrospective analysis of aHUS patients (N=35) who achieved a hematologic response after treatment with anti-C5 therapy was conducted. Clinical and demographic data were recorded and two blinded Nephropathologists scored native kidney biopsy findings independently. Seventeen histologic lesions of TMA were scored. Statistical analysis was performed using SAS version 9.4 (SAS Institute Inc., Cary, NC, USA). Association between morphology scores and CM status (n=29), renal response (n=27) and other categorical characteristics were tested using chi-squared or Fisher’s exact test as appropriate. Unpaired t-test was used for continuous variables. Significance level was set at α ≤ 0.05.

Results

In this cohort, 13/29 (45%) were CM+. Of the 17 histologic variables studied, only glomerular intracapillary fibrin differentiated CM+ from CM- (0% vs 30%, P=0.04). Histologic features were also similar between patients who achieved renal response (RR) and non-responders (NR). Although not statistically significant, NR had a higher percentage of global glomerulosclerosis (38 vs 16%, P=0.07) and concentric fibrous intimal thickening (onion skinning) (70% vs 29%, p=0.08) compared to RR.

Conclusion

Glomerular intracapillary fibrin was the only histologic variable different in CM+ versus CM- TMA. When present, this variable may suggest patients with TMA will be CM-. Percentage of glomerulosclerosis and presence of fibrous intimal thickening was higher in NR compared to RR but this did not reach statistical significance. A larger study is needed to determine the value of these features in predicting complement mutation status and renal response in aHUS.