From the Guidelines
Schistocytes are fragmented red blood cells that appear as irregularly shaped cell fragments with sharp angles and points when viewed under a microscope, indicating microangiopathic hemolytic anemia, and their presence requires immediate evaluation to identify the underlying cause, as stated in the most recent guideline update 1.
Definition and Formation
Schistocytes form when red blood cells are physically damaged as they pass through small blood vessels that are partially obstructed by fibrin strands or have damaged endothelial linings. This damage leads to the fragmentation of red blood cells, resulting in the characteristic irregular shape with sharp angles and points.
Clinical Significance
The presence of schistocytes in a peripheral blood smear is a significant finding that indicates microangiopathic hemolytic anemia. Common conditions associated with schistocytes include thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), disseminated intravascular coagulation (DIC), malignant hypertension, and mechanical heart valves.
Diagnostic Evaluation
When schistocytes are detected, immediate evaluation is necessary to identify the underlying cause. Laboratory tests should include:
- Complete blood count
- Coagulation studies
- Kidney function tests
- Assessment for hemolysis markers like lactate dehydrogenase and haptoglobin
- Blood smear morphology, as noted in the guideline update 1
Treatment and Management
Treatment focuses on addressing the underlying condition rather than the schistocytes themselves. The percentage of schistocytes correlates with disease severity, and monitoring their levels can help assess treatment response. According to the guideline update 1, management of schistocytes involves grading the severity of the condition and providing supportive care, with permanent discontinuation of immune checkpoint inhibitors in cases of severe clinical consequences.
Key Points
- Schistocytes are fragmented red blood cells that indicate microangiopathic hemolytic anemia
- Immediate evaluation is necessary to identify the underlying cause
- Laboratory tests should include complete blood count, coagulation studies, kidney function tests, and assessment for hemolysis markers
- Treatment focuses on addressing the underlying condition, with monitoring of schistocyte levels to assess treatment response, as recommended in the guideline update 1
From the Research
Definition of Schistocytes
- Schistocytes are fragmented red blood cells that are typically seen in conditions characterized by microangiopathic hemolytic anemia, such as thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS) 2, 3.
- The presence of schistocytes is often used as a diagnostic criterion for TTP/HUS, and their detection is typically performed through microscopic examination of a peripheral blood smear 2, 4.
Clinical Significance of Schistocytes
- Schistocytes are a hallmark of microangiopathic hemolytic anemia, which is a key feature of TTP/HUS 2, 3.
- The presence of schistocytes has been associated with a range of clinical conditions, including TTP, HUS, and quinine-associated thrombotic microangiopathy (TMA) 2, 3, 4.
- However, the presence of residual schistocytosis at the time of discontinuation of plasma exchange therapy has not been shown to be predictive of disease recurrence in patients with TTP 2, 5.
Laboratory Detection of Schistocytes
- Schistocytes can be detected through microscopic examination of a peripheral blood smear, and their presence is typically graded using a standardized scale 2.
- The detection of schistocytes is an important aspect of the diagnostic workup for TTP/HUS, and is often used in conjunction with other laboratory tests, such as ADAMTS13 activity assays 6, 4.