How do you approach the treatment of HSCT-associated thrombotic microangiopathy?

TMA can be due to multiple insults:

1. If the patient is on tacrolimus or cyclosporine, the dose should be reduced. These drugs cause the renal afferent arterioles to spasm, and RBC fragmentation can occur on that basis. It typically responds to a dose reduction
2. If the patient was conditioning with TBI, it could be obliterative endarteritis from XRT. In this case, you can only control blood pressure.
3. There can be vascular injury related to compound heterozygosity of complement control proteins: Factor H, Factor I, CD46, antibody to CFI, or vascular injury. In these cases, sC5b-9 should be elevated, and this is treated with narsiplomab or eculizumab.