Diagnostic Testing for Sickle Cell Disease and Sickle Cell Trait
Order hemoglobin electrophoresis, high-performance liquid chromatography (HPLC), capillary electrophoresis, mass spectrometry, or gel electrophoresis as the primary diagnostic test, and confirm with a second method such as solubility testing or electrophoresis on agar in citrate buffer. 1
Primary Diagnostic Approach
The diagnosis requires a comprehensive hemoglobinopathy screen using one of the following methods: 1
- High-performance liquid chromatography (HPLC)
- Capillary electrophoresis
- Mass spectrometry
- Gel electrophoresis
- Hemoglobin electrophoresis
Confirmation testing is mandatory—never accept a diagnosis based on a single test. 2 The second confirmatory test should be either:
Extended Red Cell Antigen Profiling
Obtain an extended red cell antigen profile by genotype or serology at the earliest opportunity, optimally before the first transfusion. 3 This profile should include at minimum: 3
- C/c
- E/e
- K
- Jk^a/Jk^b
- Fy^a/Fy^b
- M/N
- S/s
Genotyping is preferred over serologic phenotyping because it provides additional antigen information and increased accuracy, particularly for C antigen determination and Fy^b antigen matching. 3 A serologic phenotype may be inaccurate if the patient has been transfused in the last 3 months. 3
Baseline Laboratory Panel
Once diagnosis is established, obtain these baseline tests: 4, 1
Complete blood count (CBC) to assess:
Reticulocyte count to evaluate bone marrow response and hemolysis 4, 1
Markers of hemolysis: 1
- Total and direct bilirubin
- Lactate dehydrogenase (LDH)
Renal function tests: 1
- BUN
- Creatinine
Liver function tests: 1
- AST
- ALT
- Alkaline phosphatase
Critical Pitfalls to Avoid
Never use a positive sickle solubility test in isolation—it cannot differentiate between heterozygous (trait), compound heterozygous, or homozygous (disease) states. 1 This is a screening test only and requires confirmation with electrophoresis or HPLC.
Do not rely on solubility testing alone in neonates or heavily transfused patients, as false negative results can occur. 1
Always clearly communicate the diagnosis of sickle cell disease on laboratory request forms to ensure appropriate processing and interpretation. 5
Ensure the same testing method is used consistently over time for accurate trending and comparison to baseline values. 4
Newborn Screening Context
Newborn screening programs can detect sickle cell disease where available and typically use HPLC or electrophoresis methods. 1 However, confirmatory testing with a second method remains essential even when newborn screening is positive.