Initial Laboratory Tests for Suspected Acute Lymphoblastic Leukemia
For patients with suspected acute lymphoblastic leukemia (ALL), a comprehensive initial laboratory evaluation should include complete blood count (CBC) with platelets and differential, blood chemistry profile, liver function tests, disseminated intravascular coagulation panel, and tumor lysis syndrome panel. 1
Core Laboratory Tests
Essential Initial Tests
- Complete blood count (CBC) with platelets and differential 1
- Blood chemistry profile including:
- Electrolytes (including calcium and magnesium)
- Renal function (creatinine, eGFR)
- Liver function tests
- Random glucose or hemoglobin A1c
- Disseminated intravascular coagulation (DIC) panel including:
- D-dimer
- Fibrinogen
- Prothrombin time (PT)
- Partial thromboplastin time (PTT) 1
- Tumor lysis syndrome (TLS) panel including:
- Serum lactate dehydrogenase (LDH)
- Uric acid
- Potassium
- Phosphates
- Calcium 1
Diagnostic Workup for Genetic Characterization
Genetic and Molecular Testing
- Karyotyping of G-banded metaphase chromosomes (conventional cytogenetics)
- Interphase FISH assays to detect major recurrent genetic abnormalities
- Reverse transcription-polymerase chain reaction (RT-PCR) testing 1
- Should include measurement of BCR-ABL1 transcript sizes (p190 vs p210) in B-ALL
- For ETV6-RUNX1 and BCR-ABL1 negative cases, testing for other gene fusions and mutations associated with Ph-like ALL is encouraged
Additional Evaluations
Imaging Studies
- Chest X-ray to rule out mediastinal masses 1
- CT/MRI scan of the head with contrast if neurologic symptoms are observed 1
- Whole body PET/CT scan if lymphoblastic lymphoma is suspected 1
Other Important Tests
- Lumbar puncture to evaluate CNS involvement (timing should be consistent with treatment protocol) 1
- Echocardiogram or cardiac scan due to the use of anthracyclines in most treatment regimens 1
- Pregnancy testing for female patients 1
- Scrotal ultrasound for male patients if testicular involvement is suspected (more common in T-ALL) 1
Clinical Considerations and Pitfalls
Important Considerations
- The CBC is crucial as it may reveal cytopenias or abnormal cells suggestive of leukemia 2, 3
- Abnormal CBC findings should prompt further investigation with peripheral blood smear examination and bone marrow studies
- Tumor lysis syndrome can occur even before treatment in patients with high tumor burden, making the TLS panel essential 1
Common Pitfalls to Avoid
- Delaying cardiac evaluation: Assessment of cardiac function is particularly important for patients with prior cardiac history or symptoms suggestive of cardiac dysfunction 1
- Missing extramedullary disease: Thorough evaluation for extramedullary involvement, including CNS and testicular examination in males, is essential 1
- Overlooking HLA typing: HLA typing should be performed at initial workup in patients without major contraindications to hematopoietic stem cell transplantation 1
Follow-up Testing Based on Initial Results
- If initial tests suggest ALL, proceed with bone marrow aspiration and biopsy for definitive diagnosis
- Evaluate for opportunistic infections as appropriate 1
- Consider fertility counseling and preservation options for all patients 1
By following this comprehensive laboratory approach, clinicians can efficiently diagnose ALL and identify important prognostic factors that will guide treatment decisions and improve patient outcomes.