What laboratory tests should be monitored in patients with sickle cell disease?

Laboratory Monitoring in Sickle Cell Disease

For patients with sickle cell disease, routine laboratory monitoring should include complete blood count (CBC) with reticulocyte count at baseline and during comprehensive visits, with serial ferritin monitoring for those on chronic transfusion therapy, supplemented by MRI for liver iron content every 1-2 years.

Core Laboratory Monitoring

Baseline and Routine Hematologic Assessment

• Complete blood count (CBC) should be obtained at comprehensive visits to assess hemoglobin, white blood cell count, and platelet count 1
• Hemoglobin levels in steady state typically range from 7.0-11.0 g/dL, and tracking these values over time helps establish individual baseline 2
• Reticulocyte count is essential for evaluating bone marrow response and hemolysis, as it reflects the appropriateness of erythropoietic response 1
• White blood cell count has prognostic significance, as elevated WBC (>11 × 10⁹/L) is associated with increased complications and may predict vaso-occlusive crisis development 3, 4

Iron Overload Monitoring for Transfused Patients

For patients receiving chronic transfusion therapy:

• Serial ferritin levels should be monitored regularly as an inexpensive marker of total body iron burden, though inflammation can falsely elevate values 1
• MRI for liver iron content (using R2, T2*, or R2* methods) should be performed every 1-2 years, as this provides more accurate assessment than ferritin alone 1
• MRI is particularly helpful for titrating iron chelation therapy regardless of ferritin level 1
• If ferritin is <1000 ng/mL and the patient receives red cell exchange with neutral or negative iron balance, MRI may not be needed 1

Cardiac Iron Screening

• Routine cardiac T2 MRI screening is NOT recommended* for all chronically transfused patients 1
• Cardiac T2 MRI should be performed* only in high-risk subgroups: patients with liver iron content >15 mg/g for ≥2 years, evidence of end-organ damage from iron overload, or cardiac dysfunction 1
• Cardiac iron loading is less common in SCD compared to thalassemia, making routine screening less valuable 1

Acute Presentation Monitoring

During Vaso-Occlusive Crisis

• CBC with differential may be obtained, though hemoglobin and reticulocyte count changes do not typically guide admission decisions 4
• Elevated WBC count (mean 15.8 vs 12.8 × 10⁹/L) and increased delta WBC are associated with hospital admission 4
• Reticulocyte parameters including immature reticulocyte count and medium fluorescence reticulocytes (MFR) may predict future VOC development 5

During Acute Complications

• Complete blood count is essential when evaluating for acute chest syndrome, aplastic crisis, or sequestration crisis 1, 2
• Hemoglobin electrophoresis should be reserved for select scenarios when diagnosis is uncertain, as most patients have established diagnoses 1
• Lactate dehydrogenase, bilirubin, aspartate aminotransferase, and reticulocyte count may be elevated during acute ischemic priapism 1

Additional Monitoring Considerations

Renal Function Assessment

• Urinary protein evaluation should be performed annually starting at age 10 years for all genotypes 1
• Monitoring is important given impaired urinary concentrating ability and risk of renal dysfunction 1

When Initiating ACE Inhibitors or ARBs

• Adequate follow-up monitoring for hyperkalemia, cough, and hypotension is required when these medications are initiated for renal protection 1

Common Pitfalls to Avoid

• Do not rely on ferritin alone for iron overload assessment in chronically transfused patients, as inflammation falsely elevates values 1
• Do not routinely order CBC during uncomplicated vaso-occlusive crisis, as hemoglobin and reticulocyte values rarely change management 4
• Do not perform routine cardiac T2 MRI* on all transfused patients; reserve for high-risk subgroups to avoid unnecessary cost and resource utilization 1
• Ensure the same MRI method (R2, T2*, or R2*) is used consistently over time for accurate trending 1