Case Presentation: 39-year-old African American male presented with dyspnea and hematuria for one week. His past medical history includes stage 3 CKD and hypertension. In the emergency room he was found to be severely hypertensive with systolic blood pressures hovering around 240 mmHg. Initial laboratory tests revealed significantly elevated creatinine level from baseline and new-onset normocytic anemia and thrombocytopenia. He was admitted to the hospital for acute renal failure and under consideration for hemodialysis. Additional workups for acute anemia revealed hemolysis as the likely cause (low haptoglobin, elevated LDH, high absolute reticulocyte count). Peripheral blood smear also confirmed presence of schistocytes and mild thrombocytopenia. Hematology consultation was requested given concern for possible thrombotic microangiopathies (TMAs) such as thrombotic thrombocytopenic purpura (TTP) or atypical hemolytic uremic syndrome (aHUS). However, subsequent testings with ADAMTS13 assay and complement levels rendered TTP and aHUS unlikely, while direct antiglobulin test (DAT) was negative for autoimmune hemolytic anemia. Eventually, his anemia stabilized while his blood pressures were being controlled. His platelet counts also normalized shortly afterwards. A renal biopsy was later obtained to explore the cause of his renal failure, revealing moderate-to-severe arterionephrosclerosis consistent with acute hypertensive injury. His hemoglobin remained stable afterwards without any hematological intervention.

Discussion: Microangiopathic hemolytic anemia (MAHA) is characterized by intravascular red blood cell fragmentation which produces schistocytes on the peripheral blood smear. Causes of MAHA include DIC, HELLP syndrome, TTP, HUS, and malignant hypertension. The mechanism by which severe hypertension leads to MAHA is via disruption of vascular endothelium, causing fibrinoid materials to enter the vascular wall and obliterate the vascular lumen. MAHA due to severe hypertension is often difficult to distinguish from many TMAs such as TTP or HUS, especially in an acute setting. This makes clinical decision-making particularly challenging as urgent plasma exchange is frequently needed in the case of TTP. Aside from standard clinical tools such as PLASMIC score and laboratory testings, identifying the temporal relationship between hemolytic anemia and hypertension can play a key role in distinguishing TTP from hypertensive crisis and help avoid unnecessary procedures. Also, while kidney injury is often present in hypertensive crisis, rarely do patients with TTP develop severe renal dysfunction. In patients with severe hypertension-induced MAHA, control of blood pressure is the most important initial management and often the only management required.

Conclusions: Hypertensive crisis can result in MAHA and the most important management is blood pressure control. In the case of our patient, his MAHA resolved solely on blood pressure control and no further interventions were required.

IMAGE 1: Figure 1. Renal arterionephrosclerosis (H+E x20).