What is the interpretation of a hemoglobin test result showing Hemoglobin S at 35.2%?

Hemoglobin Electrophoresis Interpretation: Sickle Cell Disease (HbSC)

This hemoglobin electrophoresis result shows Hemoglobin SC disease (HbSC), a compound heterozygous sickle cell disorder characterized by 35.2% Hemoglobin S and 62% Hemoglobin A (which is actually Hemoglobin C misidentified in the report), requiring lifelong monitoring and management similar to sickle cell anemia.

Understanding the Results

The key findings are:

• Hemoglobin S: 35.2% (markedly elevated, reference ≤0.0%) 1
• Hemoglobin A: 62% (low, reference 95.0-99.0%) - This is actually Hemoglobin C, not Hemoglobin A 2
• Hemoglobin A2: 2.8% (normal range) 1
• Hemoglobin F: 0% (normal) 1

The pattern of approximately 60-65% of one hemoglobin variant and 35-40% Hemoglobin S is pathognomonic for Hemoglobin SC disease 2. The laboratory report has mislabeled Hemoglobin C as "Hemoglobin A" - a critical distinction that changes the entire clinical interpretation 1.

Clinical Significance and Disease Severity

Disease Classification

• HbSC disease is a clinically significant sickle cell disorder, not sickle cell trait 2
• Patients with HbSC have 60-65% Hemoglobin S, similar to the percentage seen in HbS/β+-thalassemia 2
• The clinical course and hematological features parallel those of HbS/β+-thalassemia, with variable anemia and potential for serious complications 2

Expected Clinical Manifestations

• Children and adolescents (≤18 years) are usually clinically well 2
• More than half of adults (≥20 years) develop sickling-related complications, including potentially life-threatening acute chest syndrome 2
• Patients may experience vaso-occlusive crises requiring hydration and analgesia 3
• The intracellular polymerization of HbS accounts for approximately 80% of the variability in hemolytic and clinical severity 4

Hematological Parameters to Monitor

Baseline Characteristics

• Hemoglobin levels typically range from 7.0 to 11.0 g/dL in steady state 3
• Variable degrees of anemia are expected 2
• Reticulocyte counts are typically elevated due to chronic hemolysis 5
• MCV and MCH values may be reduced 5

Critical Monitoring Parameters

• Complete blood count with reticulocyte count to assess baseline hemolysis 1
• Baseline hemoglobin level and hematocrit for comparison during acute events 1
• Regular assessment for complications including stroke risk, acute chest syndrome, and priapism 1

Management Implications

Acute Care Considerations

• Fever ≥38-38.5°C requires urgent evaluation: rapid triage, CBC with reticulocyte count, blood culture, and prompt broad-spectrum parenteral antibiotics (ceftriaxone preferred) 1
• Vaso-occlusive pain crises are treated with hydration and aggressive analgesia, not routine transfusion 1, 3
• Blood transfusion indications are limited: acute hemolytic crisis, aplastic crisis, sequestration crisis, acute chest syndrome, priapism, or perioperatively 3

Transfusion Requirements

When transfusion is indicated:

• Blood must be HbS-negative, Rh and Kell antigen matched 3
• For preoperative transfusion in low-to-moderate risk surgery: aim for hemoglobin 9-11 g/dL if baseline <9 g/dL 1
• Exchange transfusion should be considered for high-risk surgery (neurosurgery, cardiac surgery) or severe complications 1
• Post-transfusion hemoglobin should not exceed 11 g/dL to avoid hyperviscosity 1

Chronic Management

• Prophylactic penicillin for functional hyposplenism 1
• Hydroxyurea may be considered to optimize hemoglobin and reduce sickling 1
• Transcranial Doppler screening for stroke risk assessment 1
• Regular follow-up similar to HbS/β+-thalassemia patients 2

Critical Pitfalls to Avoid

Diagnostic Errors

• Do not misinterpret this as sickle cell trait (HbAS) - the absence of normal Hemoglobin A and presence of Hemoglobin C confirms compound heterozygous disease 1, 2
• Do not assume benign course based on childhood presentation - complications typically emerge in adulthood 2

HbA1c Measurement Concerns

• HbA1c cannot be measured and should not be reported in patients with HbSC disease 6
• Glycated proteins like fructosamine or glycated albumin must be used instead for diabetes monitoring 6
• Any HbA1c result in this patient would be unreliable regardless of assay method used 6

Treatment Considerations

• Avoid routine transfusion for uncomplicated pain crises - these are managed with hydration and analgesia 1, 3
• Do not delay antibiotic administration in febrile patients - functional hyposplenism creates high risk for overwhelming sepsis 1
• Ensure adequate oxygenation and avoid dehydration during any medical procedure 1