What tests should be ordered for a workup?

Comprehensive Workup for Diagnostic Evaluation

For a thorough diagnostic workup, order a complete blood count with differential, comprehensive metabolic panel, serum lactate dehydrogenase, serum tryptase, vitamin B12 levels, and appropriate imaging studies based on clinical presentation. 1

Initial Laboratory Testing

Essential Blood Tests

• Complete blood count (CBC) with differential and platelet count 1
• Comprehensive metabolic panel including:
  • Renal function (creatinine)
  • Liver function tests
  • Electrolytes
  • Calcium
  • Uric acid 1
• Lactate dehydrogenase (LDH) 1
• Serum tryptase levels 1
• Vitamin B12 levels 1

Additional Laboratory Testing Based on Clinical Suspicion

• Serum protein electrophoresis (SPEP) with immunofixation 1
• Serum free light chain assay 1
• Beta-2 microglobulin 1
• Coagulation studies (PT, PTT, D-dimer, fibrinogen) 1
• Erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) 1
• Quantitative immunoglobulin levels (including IgE) 1
• Tumor markers as appropriate:
  • Alpha-fetoprotein (AFP) 1
  • Beta-human chorionic gonadotropin (β-HCG) 1
  • Prostate-specific antigen (PSA) in males 1

Imaging Studies

Initial Imaging

• CT scan of chest, abdomen, and pelvis with oral and intravenous contrast 1
• Consider PET/CT if lymphoma or unknown primary malignancy is suspected 1

Additional Imaging Based on Clinical Presentation

• MRI of brain if neurological symptoms are present 1
• Chest X-ray to rule out mediastinal masses 1
• Whole-body MRI or low-dose CT for suspected plasma cell disorders 1

Specialized Testing

Bone Marrow Evaluation

• Bone marrow aspirate and biopsy with:
  • Immunohistochemistry (IHC) for CD117, CD25, tryptase 1
  • Conventional cytogenetics 1
  • Flow cytometry for immunophenotyping 1
  • FISH or RT-PCR for genetic abnormalities 1

Molecular and Genetic Testing

• Next-generation sequencing (NGS) panels for myeloid mutations when appropriate 1
• Chromosomal microarray (CMA) for suspected developmental disorders 1
• FISH for specific translocations in suspected hematologic malignancies 1

Disease-Specific Considerations

For Suspected Eosinophilic Disorders

• Peripheral blood smear review 1
• Serology testing for parasitic infections 1
• Stool ova and parasites test 1
• Aspergillus IgE for allergic bronchopulmonary aspergillosis 1

For Suspected Hematologic Malignancies

• Flow cytometry of peripheral blood and/or bone marrow 1
• Lumbar puncture for cerebrospinal fluid analysis if CNS involvement is suspected 1
• MUGA scan or echocardiogram if anthracycline-based therapy is anticipated 1

For Cancer of Unknown Primary

• Thorough physical examination including head and neck, rectal, pelvic, and breast examination 1
• Fecal occult blood testing 1
• Immunohistochemistry on tissue samples to determine tissue of origin 1

Common Pitfalls to Avoid

1. Incomplete evaluation: Failing to order both CBC and comprehensive metabolic panel can miss critical diagnostic clues 2, 3

2. Overlooking specialized testing: For suspected hematologic disorders, bone marrow evaluation is essential even if peripheral blood appears normal 1

3. Inadequate imaging: Using only plain radiographs when cross-sectional imaging would provide more diagnostic information 1

4. Missing genetic testing: Particularly important in developmental disorders and certain hematologic malignancies 1

5. Not considering age-specific testing: Different age groups may require tailored diagnostic approaches 1

By following this comprehensive approach to diagnostic workup, clinicians can efficiently identify underlying conditions and develop appropriate treatment strategies that will positively impact patient morbidity, mortality, and quality of life.