De novo thrombotic microangiopathy after kidney transplantation: clinical features, treatment, and long-term patient and graft survival

INTRODUCTION

Posttransplant thrombotic microangiopathy (TMA)/hemolytic uremic syndrome (HUS) can occur as a recurrent or de novo disease.

METHODS

A retrospective single-center observational study was applied in order to examine the incidence and outcomes of de novo TMA/HUS among transplantations performed between 2000 and 2010. Recurrent HUS or antibody-mediated rejections were excluded.

RESULTS

Seventeen (1.1%) among 1549 kidney transplant recipients fulfilled criteria for de novo TMA. The mean follow-up was 572 days (range, 69-1769). Maintenance immunosuppression was prednisone, tacrolimus (TAC), and mycophenolic acid in 14 (82%) patients. Mean age at onset was 40 ± 15 years, and serum creatinine was 6.1 ± 4.1 mg/dL. TMA occurred at a median of 25 days (range, 1-1755) after transplantation. Nine (53%) patients developed TMA within 1 month of transplantation and only 12% after 1 year. Clinical features were anemia (hemoglobin < 10 g/dL) in 9 (53%) patients, thrombocytopenia in 7 (41%), and increased lactate dehydrogenase in 12 (70%). Decreased haptoglobin was observed in 64% and schistocytes in 35%. Calcineurin inhibitor (CNI) withdrawal or reduction was the first step in the management of 10/15 (66%) patients, and 6 (35%) received fresh frozen plasma (FFP) and/or plasmapheresis. TAC was successfully reintroduced in six patients after a median of 17 days. Eight (47%) patients needed dialytic support after TMA diagnosis and 75% remained on dialysis. At 4 years of follow-up, death-censored graft survival was worse for TMA group (43.0% versus 85.6%, log-rank = 0.001; hazard ratio = 3.74) and there was no difference in patient survival (53.1% versus 82.2%, log-rank = 0.24).

CONCLUSION

De novo TMA after kidney transplantation is a rare but severe condition with poor graft outcomes. This syndrome may not be fully manifested, and clinical suspicion is essential for early diagnosis and treatment, based mainly in CNI withdrawal and FFP infusions and/or plasmapheresis.

Lupus nephritis is more severe in children and adolescents than in older adults

OBJECTIVE

To evaluate clinicopathological features and treatment response in patients with lupus nephritis (LN), comparing the childhood- and late-onset forms of the disease.

METHODS

We retrospectively analyzed clinical presentation, treatment and evolution in patients diagnosed with LN by renal biopsy between 1999 and 2008. Patients were grouped by age-≤18 years (n = 23); and ≥50 years (n = 13)-and were followed for the first year of treatment.

RESULTS

The baseline features of the childhood- and late-onset groups, respectively, were as follows: mean age, 15 ± 2 and 54 ± 5 years; female gender, 87% and 92%; hypertension, 87% and 77%; Systemic Lupus Erythematosus Disease Activity Index, 29 ± 9 and 17 ± 7 (p = 0.002); estimated glomerular filtration rate (eGFR), 86 ± 66 and 70 ± 18 ml/min; concurrent SLE/LN diagnosis, 90% and 15% (p < 0.001); crescents on biopsy, 74% and 30% (p = 0.02); activity index on biopsy, 4.8 ± 2.6 and 3.3 ± 1.9 (p = 0.10); and interstitial fibrosis (>10%), 39% and 61% (p = 0.08). Treatment consisted mainly of methylprednisolone, prednisone and intravenous cyclophosphamide, average cumulative doses being similar between the groups. After 12 months of treatment, the eGFR in the younger and older patients was 116 ± 62 and 78 ± 20 ml/min, respectively (p = 0.005). Three of the younger patients progressed to dialysis at 12 months, compared with none of the older patients.

CONCLUSION

Childhood-onset LN seems to be more severe than is late-onset LN.