Clinical features and outcomes in patients with thrombotic microangiopathy not associated with severe ADAMTS13 deficiency

Persistently elevated sFlt-1 and recovery of reduced ADAMTS13 activity in malignant hypertension

BACKGROUND AND OBJECTIVES

Malignant hypertension (MHT) characterized by acute hypertension with retinopathy or multiorgan damage, is a severe form of hypertensive emergency and associated with target organ involvement and poor kidney outcome. However, the underlying mechanisms are unclear.

METHODS

Eighty-four patients with acute severe hypertension from the Nephrology Department and Emergency Department in a single center during January 2016 and December 2017 were prospectively enrolled and divided into MHT ( n  = 48) and non-MHT ( n  = 36) subgroups according to target organ evaluation. Forty healthy controls were recruited. Serum soluble Fms-like tyrosine kinase-1 (sFlt-1) levels and plasma ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motif, member 13) activity were examined at baseline and 12-month follow-up. Renal endpoints were defined as a significant decrease in the estimated glomerular filtration rate (eGFR) of more than 40% or the occurrence of end-stage renal disease.

RESULTS

Serum sFlt-1 levels were persistently elevated in MHT. Baseline serum sFLT-1 levels were correlated with plasma ADAMTS13 activity and markers of target organ damage. Plasma ADAMTS13 activity was reduced in both MHT and non-MHT patients and recovered to the normal range at 12-month follow-up. During an average follow-up time of 53 ± 13 months, the restoration of reduced ADAMTS13 activity was correlated with the improvement of kidney function and independently reduced the risk of renal endpoints.

CONCLUSIONS

Abnormal angiogenesis and endothelial damage are involved in the pathophysiology of hypertensive emergency. Evaluation of ADAMTS13 and sFlt-1 may help in the diagnosis and assessment of MHT. Recovery of ADAMTS13 predicts better renal outcome in patients with hypertensive emergencies.

Non-Alloimmune Mechanisms of Thrombocytopenia and Refractoriness to Platelet Transfusion

Refractoriness to platelet transfusion is a common clinical problem encountered by the transfusion medicine specialist. It is well recognized that most causes of refractoriness to platelet transfusion are not a consequence of alloimmunization to human leukocyte, platelet-specific, or ABO antigens, but are a consequence of platelet sequestration and consumption. This review summarizes the clinical factors that result in platelet refractoriness and highlights recent data describing novel biological mechanisms that contribute to this clinical problem.

Successful plasma exchange in a 34-year-old woman with diabetic ketoacidosis and a thrombotic microangiopathy

Thrombotic microangiopathy (TMA) associated with diabetic ketoacidosis (DKA) is a rare complication reported in the pediatric setting. We report a case of an adult patient with new-onset DM, DKA, and TMA who was treated successfully with therapeutic plasma exchange (TPE). The patient underwent five procedures and experienced quick recovery in her platelet count and a near-normalization of her LDH. Within 3 days, ADAMTS13 activity was reported at 40.7% (>66.8%). After a protracted hospital course, mostly focused on treating the patient's bilateral hemorrhagic chemosis, the patient was discharged on hospital day 30. TMA is associated with a spectrum of diseases such as TTP and sepsis but, to our knowledge, it has not been reported in the setting of DKA in an adult patient. Evidence supports that metabolic alterations associated with DKA and its treatment disrupt basal hemostatic mechanisms and promote a thrombotic state. Although ADAMTS13 activity was only moderately decreased, our patient responded rapidly to TPE, with a striking increase and stabilization of her PLT count that was durable beyond discharge. As reported recently, patients who have TMA with ADAMTS13 activity levels >10% have a range of diagnoses, presentations, and outcomes. Although the underlying microangiopathic process is incompletely understood, these patients may respond well to TPE, as was seen in this case.

Deficiency of complement factor H-related proteins and autoantibody-positive hemolytic uremic syndrome in an infant with combined partial deficiencies and autoantibodies to complement factor H and ADAMTS13

A 3-month-old male infant developed an extremely severe episode of atypical hemolytic uremic syndrome (aHUS) associated with partial deficiencies of full-length complement factor H (FH; ∼15% of infant normal) and a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) (39% of normal) and autoantibodies reactive with both proteins. His FH and ADAMTS13 genes were normal, indicating that the partial deficiencies were acquired, probably as the result of autoantibodies against full-length FH and ADAMTS13. The child also had a homozygous deletion of the complement factor H–related (CFHR)3–CFHR1 portion in the complement factor H (CFH) gene cluster. He therefore had deficiency of CFHR proteins and autoantibody-positive hemolytic uremic syndrome (DEAP-HUS) with an unusual early onset associated with a partial deficiency of ADAMTS13 and an anti-ADAMTS13 autoantibody. His clinical episode of aHUS responded to plasma infusion and subsequent treatment with mycophenolate and rituximab. We believe that this is the first report of DEAP-HUS in an infant with partial deficiencies in both ADAMTS13 and full-length FH acquired in association with autoantibodies to both proteins.