Algorithm for the evaluation of TMA after HSCT. Screening for TMA includes monitoring LDH, complete blood count, and routine urinalyses. TMA should be suspected in HSCT recipients with an acute elevation of LDH, proteinuria >30 mg/dL, and hypertension more severe than expected with calcineurin or steroid therapy, usually requiring >2 antihypertensive medications. Clinical interventions should be considered for patients with both proteinuria >30 mg/dL and elevated sC5b-9.