From the Guidelines
There is no specific diagnostic test that can definitively rule in vaso-occlusive episodes (VOEs) in sickle cell patients, and diagnosis is primarily based on clinical presentation and patient history. VOEs are characterized by acute severe pain in the extremities, back, chest, or abdomen, consistent with previous pain crises. While laboratory tests such as complete blood count (CBC) may show decreased hemoglobin levels and elevated white blood cell counts, as noted in a 2021 study published in The Journal of Urology 1, these findings are nonspecific and can be associated with various conditions.
- A reticulocyte count may be used in the evaluation and management of patients with sickle cell disease during presentations of acute vaso-occlusive crisis, as mentioned in the same study 1.
- Hemoglobin electrophoresis can confirm sickle cell disease but does not identify acute crises.
- Imaging studies such as X-rays, CT scans, or MRIs may help identify complications like avascular necrosis or acute chest syndrome but do not diagnose the VOE itself. The diagnosis of VOEs remains challenging because it relies heavily on subjective pain assessment and exclusion of other conditions that might cause similar symptoms, reflecting the pathophysiology of VOEs, which involve sickle-shaped red blood cells blocking small blood vessels, leading to ischemia, inflammation, and pain in affected tissues.
From the Research
Diagnostic Tests for Vaso-Occlusive Episodes in Sickle Cell Patients
- The complete blood count (CBC) and reticulocyte count may not be necessary in the evaluation of acute vasoocclusive sickle-cell crisis 2
- A combination of routine laboratory biomarkers, such as reticulocyte count, immature reticulocyte count, and fluorescent reticulocyte fraction, may be used to predict vaso-occlusive crisis (VOC) development in sickle cell disease (SCD) 3
- A novel red blood cell deformability biomarker, which measures the proportion of RBCs deformable enough to exhibit a specific tank-treading motion in shear flow, may be associated with hemolysis and vaso-occlusive crises in SCD 4
- Various hematological and biochemical parameters, such as percent sickling, P50 for O2, CBC profile, PO2, serum calcium, ALP, LDH, alpha-HBD level, zinc and calcium levels in plasma and in RBC, may vary between crisis and non-crisis states of frequent sicklers and also between frequent sicklers and infrequent sicklers 5
Laboratory Biomarkers
- Reticulocyte count: increased in SCD patients with VOC development compared to SCD patients without VOC development 3
- Immature reticulocyte count: increased in SCD patients with VOC development compared to SCD patients without VOC development 3
- Fluorescent reticulocyte fraction: increased in SCD patients with VOC development compared to SCD patients without VOC development 3
- Medium fluorescence reticulocytes (MFR): increased in SCD patients with VOC development compared to SCD patients without VOC development 3
Potential Diagnostic Tests
- A point-of-care or companion diagnostic device that measures red blood cell deformability may be developed for personalized medicine 4
- A combination of routine laboratory biomarkers, such as reticulocyte count, immature reticulocyte count, and fluorescent reticulocyte fraction, may be used to predict VOC development in SCD 3