Table 5.

Characteristic features of renal failure in TTP

•	Hematuria and proteinuria are common in patients with acquired TTP during acute exacerbation.
•	Renal function impairment is mild and reversible in most cases of acquired TTP. Chronic renal failure may occur if the course of TTP is protracted.
•	Acute renal failure occurs in very few patients with acquired ADAMTS13 deficiency. Concurrent disorders may cause or contribute to the severity of renal failure
•	Acute and chronic renal failures are not infrequent in patients with hereditary TTP, affecting approximately 10% of the reported cases.
•	A concurrent factor H mutation has been detected in a patient whose hereditary TTP was complicated with acute and chronic renal failures.
•	Expression of ADAMTS13 in glomerular endothelial cells and podocytes may contribute to the cleavage of VWF locally in the glomeruli of patients with acquired TTP, minimizing the severity of their renal thrombosis and functional impairment. On the other hand, deficient ADAMTS13 expression in podocytes may account for the higher risk of renal failure in patients with hereditary TTP.
•	Urinalysis and renal function should be monitored in patients with TTP during remission. To minimize the risk of chronic injury to the kidney and other vital organs, maintenance plasma therapy should be considered for most patients with hereditary TTP, particularly if the patient has developed acute renal failure during exacerbations, evidence of progressive decline of the glomerular filtration rate, or has chronic hematuria and/or proteinuria.
•	The dose and frequency of maintenance plasma therapy should be sufficient to prevent acute exacerbations, stabilize the renal function, and minimize the severity of hematuria and proteinuria.
•	Investigation for other causes should be pursued if the course of renal deterioration is unexpectedly swift or unresponsive to plasma therapy.