Laboratory Tests for Sickle Cell Crisis

Essential Laboratory Tests

• A comprehensive laboratory panel should include complete blood count, markers of hemolysis, renal and liver function tests, and coagulation studies to assess the severity of the crisis and detect potential organ damage, as recommended by the American Society of Anesthesiologists 1, 2
• Hemoglobin level should be assessed to evaluate the severity of anemia, which results from hemolysis 3
• White blood cell count may be elevated in acute crisis and can indicate infection or inflammation, according to the American Urological Association 4
• Reticulocyte count should be evaluated to assess bone marrow response to hemolysis, as suggested by the American Urological Association 4
• Bilirubin (total and direct) levels are increased due to red cell breakdown, as indicated by the American Urological Association 4
• Blood urea nitrogen (BUN) and creatinine levels should be assessed to evaluate for acute kidney injury, which can occur due to vaso-occlusion, as recommended by the American Society of Anesthesiologists 1, 2
• Electrolytes should be monitored to detect imbalances that may occur due to renal dysfunction or dehydration, according to the American Society of Anesthesiologists 1
• Urinalysis should be performed to check for hematuria, proteinuria, or signs of urinary tract infection, as suggested by the American Society of Anesthesiologists 2
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels may be elevated due to liver involvement, as indicated by the American Urological Association 4
• Alkaline phosphatase levels can be increased with hepatobiliary involvement, according to the American Society of Anesthesiologists 2
• Prothrombin time (PT) and partial thromboplastin time (PTT) should be assessed to evaluate for coagulopathy, as recommended by the American Society of Anesthesiologists 5

Specialized Tests Based on Clinical Presentation

• Arterial blood gas should be assessed to evaluate oxygenation and acid-base status in patients with acute chest syndrome, as suggested by the American Society of Anesthesiologists 1
• Blood cultures should be performed if infection is suspected as a trigger for acute chest syndrome, according to the American Society of Anesthesiologists 3
• Corporal blood gas should be evaluated to differentiate ischemic from non-ischemic priapism, as indicated by the American Urological Association 4
• Previous transcranial Doppler study results should be reviewed, especially in children with suspected stroke, as recommended by the American Society of Anesthesiologists 6

Rationale for Laboratory Testing

• Hemolysis is a central feature of sickle cell crisis, leading to anemia and potential organ damage, as stated by the American Society of Anesthesiologists 3
• Vaso-occlusion causes tissue ischemia, which can lead to organ dysfunction and failure, according to the American Society of Anesthesiologists 3

Important Considerations

• Baseline laboratory values should be known for comparison, as many patients with sickle cell disease have chronic abnormalities, as recommended by the American Society of Anesthesiologists 1
• Laboratory abnormalities should be interpreted in the context of the patient's clinical presentation, according to the American Society of Anesthesiologists 2

Pitfalls to Avoid

• Relying solely on hemoglobin levels to determine the need for transfusion - consider the patient's baseline hemoglobin and clinical status, as suggested by the American Society of Anesthesiologists 1
• Failing to monitor for complications of treatment, such as fluid overload or transfusion reactions, according to the American Society of Anesthesiologists 5
• Not communicating the diagnosis of sickle cell disease clearly on laboratory request forms, which may delay appropriate processing and interpretation, as recommended by the American Society of Anesthesiologists 7

Laboratory Tests Indicating Sickle Cell Crisis

Essential Laboratory Findings in Acute Crisis

• Hemoglobin level drops acutely from baseline due to hemolysis, though the absolute value must be interpreted against the patient's chronic baseline in patients with HbSS, typically 6-9 g/dL 8
• Review of previous transcranial Doppler results from within 12 months (or 24 months for HbSC/HbSβ+ thalassemia) is recommended, especially in children suspected of having a stroke 9

Pre-operative Laboratory Requirements

• For surgical patients with sickle cell disease, the American College of Surgeons recommends obtaining full blood count, urea and electrolytes, and complete red cell antibody screen before any procedure, with repeat tests within 72 hours of surgery if transfused within 3 months 9