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Abstract: FR-PO884

Renal Thrombotic Microangiopathy in Lupus Nephritis (LN)

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Strufaldi, Fernando Louzada, Hospital das clínicas - Faculdade de Medicina da USP, Sao Paulo, Brazil
  • Dias, Cristiane B., University of Sao Paulo, Brazil, São Paulo, Brazil
  • Yu, Luis, University of Sao Paulo School of Medicine, Sao Paulo, Brazil
  • Woronik, Viktoria, University of Sao Paulo School of Medicine, Sao Paulo, Brazil
  • Malheiros, Denise M., University of Sao Paulo, Sao Paulo, Brazil
  • Cavalcante, Livia Barreira, Hospital das Clinicas da Faculdade de Medicina da USP , Sao Paulo, Brazil
  • Jorge, Lectícia, University of São Paulo, São Paulo, Brazil
Background

Renal thrombotic microangiopathy (rTMA) is one out of many vascular findings in LN. However, the influence of rTMA on prognosis and its related factors has not been well established. Therefore, the objective of this study was to evaluate the clinical and pathological aspects of patients with rTMA in kidney biopsy.

Methods

Analysis of medical reports database and kidney biopsy of 253 patients who had biopsy-proven LN, between January 2012 and December 2018 in our Hospital. We performed comparative analyses between groups with and without rTMA in kidney biopsy.

Results

Forty-three (17%) of 253 patients showed rTMA on kidney histology. This group had a significantly lower glomerular filtration rate (GFR) estimated by CKD-EPI formula (ml/min/1.73m2) at the time of biopsy (40.5±38.2 vs. 71.6±40.6, p<0.001), at 1 year of follow-up (50.7±48.7 vs. 83.5±40.4, p<0.001), and at the end of follow-up (47.7±50.5 vs. 80.3±38.3, p< 0.001). Significantly more patients in the rTMA group reached the composite end-point of hemodialysis, death or GFR < 15 (79.5% vs.31.8%, p < 0.001). Patients with histological findings of microangiopathy had a lower mean of Hb, platelets and haptoglobin (10.3± 1.6 vs.11.1±1.5 p=0.0018, 194±88 vs. 253±92 p=0.0001 and 119±86 vs 160±104 p=0.02 respectively) and a higher LDH (391± 209 vs 303±147 p=0.008). However, if the classical diagnostic criteria for microangiopathic anemia (Hb <12, hapto <10 high DHL and platelet <150) were applied, no patient fulfilled the entire criterion. As expected, TMA group showed higher blood pressure (SBP 131±10.5 vs 124±17.3 p=0.01). There was no difference between groups concerning C3, C4, ANA, anti-Ro, and anti-La. Concerning histopathological features, rTMA group had significantly higher activity (9.0±4.8 vs. 6.0±4.5, p=0.001) and chronicity (4.4±2.9 vs. 2.7±2.2, p =0.001) scores. On the other hand, there was no difference in immunofluorescence.

Conclusion

The classical criterion of microangiopathic hemolytic anemia was not able to predict rTMA. For NL patients, these criteria could be more flexible. Serological data were also not predictors. Renal biopsy remains the critical method for diagnosis and rTMA was a frequent and serious finding. RTMA was an important risk factor for renal outcome, as demonstrated by lower GFR and higher hemodialysis rates in this group.